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In this work, we utilize the framework of many-body expansion (MBE) to decompose electronic structures into fragments by incrementing virtual orbitals, aiming to accurately solve the ground and excited state energies of each fragment using the variational quantum eigensolver and deflation algorithms. While our approach is primarily based on unitary coupled cluster singles and doubles (UCCSD) and its generalization, we also introduce modifications and approximations to conserve quantum resources in MBE by partially generalizing the UCCSD operator and neglecting the relaxation of the reference states. As a proof of concept, we investigate the potential energy surfaces for the bond-breaking processes of the ground state of two molecules (H 2 O and N 2 ) and calculate the ground and excited state energies of three molecules (LiH, CH + , and H 2 O). The results demonstrate that our approach can, in principle, provide reliable descriptions in all the tests including strongly correlated systems when appropriate approximations are chosen. Additionally, we perform model simulations to investigate the impact of shot noise on the total MBE energy and show that precise energy estimation is crucial for lower-order MBE fragments.

We propose a quantum inverse algorithm (QInverse) to directly determine general eigenstates by repeatedly applying the inverse power of a shifted Hamiltonian to an arbitrary initial state. To properly deal with the strongly entangled inverse power states and the resultant excited states, we solved the underlying linear equation, both variationally and adaptively, to obtain a faithful inverse power state with a shallow quantum circuit. QInverse is singularity-free and successfully obtains the target excited states with an energy closest to the shift ω, which is difficult to reach using variational methods. We also propose a subspace expansion approach to accelerate convergence and show that it is helpful to determine the two nearest eigenvalues when they are equally close to ω. These approaches were compared with the folded-spectrum method, which aims to generate excited states through variational optimization. It is shown that, whereas the folded-spectrum approach often fails to predict the target state by falling into a local minimum owing to its variational features, the success rate and accuracy of our algorithms are systematically improvable.

Quantum imaginary time evolution (QITE) is a recently proposed quantum-classical hybrid algorithm that is guaranteed to reach the lowest state of systems. In this study, we present several improvements on QITE, mainly focusing on molecular applications. We analyze the derivation of the underlying QITE equation order-by-order and suggest a modification that is theoretically well founded. Our results clearly indicate the soundness of the here-derived equation, enabling a better approximation of the imaginary time propagation by a unitary. We also discuss how to accurately estimate the norm of an imaginary-time-evolved state and applied it to excited-state calculations using the quantum Lanczos algorithm. Finally, we propose the folded-spectrum QITE scheme as a straightforward extension of QITE for general excited-state simulations. The effectiveness of all these developments is illustrated by simulations with or without noise effect, offering further insights into quantum algorithms for imaginary time evolution.

Dopant segregation, frequently observed in ionic oxides, is useful for engineering materials and devices. However, due to the poor driving force for ion migration and/or the presence of substantial grain boundaries, dopants are mostly confined within a nanoscale region. Herein, we demonstrate that core-shell heterostructures are formed by oriented self-segregation using one-step thermal annealing of metal-doped hematite mesocrystals at relatively low temperatures in air. The sintering of highly ordered interfaces between the nanocrystal subunits inside the mesocrystal eliminates grain boundaries, leaving numerous oxygen vacancies in the bulk. This results in the efficient segregation of dopants (~90%) on the external surface, which forms their oxide overlayers. The optimized photoanode based on hematite mesocrystals with oxide overlayers containing Sn and Ti dopants realises high activity (~0.8 μmol min -1 cm -2 ) and selectivity (~90%) for photoelectrochemical H 2 O 2 production, which provides a wide range of application for the proposed concept., (© 2022. The Author(s).)

This article summarizes technical advances contained in the fifth major release of the Q-Chem quantum chemistry program package, covering developments since 2015. A comprehensive library of exchange-correlation functionals, along with a suite of correlated many-body methods, continues to be a hallmark of the Q-Chem software. The many-body methods include novel variants of both coupled-cluster and configuration-interaction approaches along with methods based on the algebraic diagrammatic construction and variational reduced density-matrix methods. Methods highlighted in Q-Chem 5 include a suite of tools for modeling core-level spectroscopy, methods for describing metastable resonances, methods for computing vibronic spectra, the nuclear-electronic orbital method, and several different energy decomposition analysis techniques. High-performance capabilities including multithreaded parallelism and support for calculations on graphics processing units are described. Q-Chem boasts a community of well over 100 active academic developers, and the continuing evolution of the software is supported by an "open teamware" model and an increasingly modular design.

In this study, we continue to develop the recently proposed second-order perturbation theory for the spin-projected Hartree-Fock method [Tsuchimochi, T.; Ten-no, S. L. J. Chem. Theory Comput. 2019, 15, 6688] in various aspects. A new, stable imaginary level-shift scheme is derived to obtain a well-conditioned equation, enabling a significantly faster convergence. To achieve a further speed-up, we propose a preconditioning scheme considering the pair character on a spin-projected basis. We also eliminate the computational memory bottleneck in solving the linear equation for large systems using a distributed memory parallel implementation. Finally, for the description of open-shell molecules, several modified zeroth-order Hamiltonians are introduced and tested using the Mn 2 O 2 (NHCHCO 2 ) 4 complex. These developments enable practical calculations of a second-order perturbation theory with improved accuracy at a reduced computational cost.

We propose two different schemes for second-order perturbation theory with spin-projected Hartree-Fock. Both schemes employ the same ansatz for the first-order wave function, which is a linear combination of spin-projected configurations. The first scheme is based on the normal-ordered projected Hamiltonian, which is partitioned into the Fock-like component and the remaining two-particle-like contribution. In the second scheme, the generalized Fock operator is used to construct a spin-free zeroth-order Hamiltonian. To avoid the intruder state problem, we adopt the level-shift techniques frequently used in other multireference perturbation theories. We describe both real and imaginary shift schemes and compare their performances on small systems. Our results clearly demonstrate the superiority of the second perturbation scheme with an imaginary shift over other proposed approaches in various aspects, giving accurate potential energy curves, spectroscopic constants, and singlet-triplet splitting energies. We also apply these methods to the calculation of spin gaps of transition-metal complexes as well as the potential energy curve of the chromium dimer.

Microbacterium species are coryneform gram-positive rods that are widely distributed in the environment and have been recently recognized as rare pathogens in humans. However, information about the epidemiologic and clinical characteristics of Microbacterium species is scarce. We herein reported an 11-year-old girl with acute leukemia who was found to have catheter-related bloodstream infection in her neutropenic phase. Gram-positive bacilli repeatedly grew on the blood cultures and were later confirmed by 16S rRNA analysis as Microbacterium paraoxydans. A literature review found available clinical courses in 21 cases (7 pediatric cases) of Microbacterium spp. bacteremia. Our case and those in literature suggested that Microbacterium spp. bacteremia often occurs in patients with indwelling central venous catheters; the literature review further suggested that removal of central venous catheters is required in most cases and that 16S rRNA sequence was useful in identifying in detail the species of Microbacterium., (Copyright © 2019 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Recently, we introduced an orbital-invariant approximate coupled-cluster (CC) method in the spin-projection manifold. The multi-determinantal property of spin-projection means that the parametrization in the spin-extended CC (ECC) ansatz is nonorthogonal and overcomplete. Therefore, the linear dependencies must be removed by an orthogonalization procedure to obtain meaningful solutions. Multi-reference methods often achieve this by diagonalizing a metric of the equation system, but this is not feasible with ECC because of the enormous size of the metric, a consequence of the incomplete active space of the spin-projected Hartree-Fock reference. As a result, the applicability of ECC has been limited to small benchmark systems, for which the ansatz was shown to be superior to the configuration interaction and linearized approximations. In this article, we provide a solution to this problem that completely avoids the metric diagonalization by iteratively projecting out its null-space from the working equations. As the additional computational cost required for this iterative projection is only marginal, it greatly expands the application range of ECC. We demonstrate the potential of approximate ECC by studying the complete basis set limit of F 2 and transition metal complexes such as NiO, Mn 2 , and [Cu 2 O 2 ] 2+ , which have all been hindered by the prohibitively large metric size. We also identify the potential inadequacy of the molecular orbitals given by spin-projected Hartree-Fock in some cases, and propose possible solutions. © 2018 Wiley Periodicals, Inc., (© 2018 Wiley Periodicals, Inc.)

We present an approximate treatment of spin-extended coupled-cluster (ECC) based on the spin-projection of the broken-symmetry coupled-cluster (CC) ansatz. ECC completely eliminates the spin-contamination of unrestricted CC and is therefore expected to provide better descriptions of dynamical and static correlation effects, but introduces two distinct problems. The first issue is the emergence of non-terminating amplitude equations, which are caused by the de-excitation effects inherent in symmetry projection operators. In this study, we take a minimalist approach and truncate the Taylor series of the exponential ansatz at a certain order such that the approximation safely recovers the traditional CC without spin-projection. The second issue is that the nonlinear equations of ECC become underdetermined, although consistent, yielding an infinitude of solutions. This problem arises because of the redundancies in the excitation manifold, as is common in other multi-reference approaches. We remove the linear dependencies in ECC by employing an orthogonal projection manifold. We also propose an efficient solver for our method, in which the components are usually sparse but not diagonal-dominant. It is shown that our approach is rigorously orbital-invariant and provides more accurate results than its configuration interaction and linearized CC analogues for chemical systems.

We propose a size-consistent generalization of the recently developed spin-extended configuration interaction with singles and doubles (ECISD), where a CI wave function is explicitly spin-projected. The size-consistent effect is effectively incorporated by treating quadruples within the formulation of coupled electron pair approximation. As in coupled-cluster theory, quadruple excitations are approximated by a disconnected product of double excitations. Despite its conceptual similarity to the standard single-reference and multireference analogues, such a generalization requires careful derivation, as the spin-projected CI space is nonorthogonal and overcomplete. Although our methods generally yield better results than ECISD, size-consistency is only approximately retained because the action of a symmetry-projection operator is size-inconsistent. In this work, we focus on simple models where exclusion-principle-violating terms, which eliminate undesired contributions to the correlation effects, are either completely neglected or averaged. These models possess an orbital-invariant energy functional that is to be minimized by diagonalizing an energy-shifted effective Hamiltonian within the singles and doubles manifold. This allows for a straightforward generalization of the ECISD analytical gradients needed to determine molecular properties and geometric optimization. Given the multireference nature of the spin-projected Hartree-Fock method, the proposed approaches are expected to handle static correlation, unlike single-reference analogues. We critically assess the performance of our methods using dissociation curves of molecules, singlet-triplet splitting gaps, hyperfine coupling constants, and the chromium dimer. The size-consistency and size-extensivity of the methods are also discussed.

In electronic structure theory, the availability of an analytical derivative is one of the desired features for a method to be useful in practical applications, as it allows for geometry optimization as well as computation of molecular properties. With the recent advances in the development of symmetry-projected Hartree-Fock (PHF) methods, we here aim at further extensions by devising the analytic gradients of post-PHF approaches with a special focus on spin-extended (spin-projected) configuration interaction with single and double substitutions (ECISD). Just like standard single-reference methods, the mean-field PHF part does not require the corresponding coupled-perturbed equation to be solved, while the correlation energy term needs the orbital relaxation effect to be accounted for, unless the underlying molecular orbitals are variationally optimized in the presence of the correlation energy. We present a general strategy for post-PHF analytical gradients, which closely parallels that for single-reference methods, yet addressing the major difference between them. The similarity between ECISD and multi-reference CI not only in the energy but also in the optimized geometry is clearly demonstrated by the numerical examples of ozone and cyclobutadiene.

Strong correlation poses a difficult problem for electronic structure theory, with computational cost scaling quickly with system size. Fragment embedding is an attractive approach to this problem. By dividing a large complicated system into smaller manageable fragments "embedded" in an approximate description of the rest of the system, we can hope to ameliorate the steep cost of correlated calculations. While appealing, these methods often converge slowly with fragment size because of small errors at the boundary between fragment and bath. We describe a new electronic embedding method, dubbed "Bootstrap Embedding," a self-consistent wavefunction-in-wavefunction embedding theory that uses overlapping fragments to improve the description of fragment edges. We apply this method to the one dimensional Hubbard model and a translationally asymmetric variant, and find that it performs very well for energies and populations. We find Bootstrap Embedding converges rapidly with embedded fragment size, overcoming the surface-area-to-volume-ratio error typical of many embedding methods. We anticipate that this method may lead to a low-scaling, high accuracy treatment of electron correlation in large molecular systems.

In our recent Communication (J. Chem. Phys. 2016, 144, 011101), we proposed Wick's theorem for nonorthogonal determinants and applied it to spin-extended configuration interaction with singles and doubles (ECISD) based on spin-projected unrestricted Hartree-Fock (SUHF), given that SUHF is a special case of nonorthogonal CI. It was shown that ECISD is accurate for bond-dissociation processes of several representative molecules. In the present work, we give a detailed derivation of ECISD and report an efficient implementation with two physically motivated preconditioning schemes in the generalized Davidson diagonalization for ECISD, whose Hamiltonian and overlap are not diagonal dominant due to SUHF's nonorthogonal character. In the first approach, we exploit the properties of corresponding pair orbitals and spin-projection operator and rotate the spin-projected CI basis so that the Hamiltonian is approximately diagonal. The second scheme is based on the normal ordered Hamiltonian, which suggests neglecting the expensive two-particle terms in the preconditioning. To enable frozen-core approximations in ECISD, core orbitals were introduced in SUHF. We also show the validity of our method with various numerical examples for static correlations, apart from the left-right correlation in bond-dissociation processes: the ground state energies of the Be isoelectronic series, excitation energies of representative small molecules, and spectroscopic constants of the strongly correlated BN singlet state. Several aspects of ECISD were studied.

We present single and double particle-hole excitations in the recently revived spin-projected Hartree-Fock. Our motivation is to treat static correlation with spin-projection and recover the residual correlation, mostly dynamic in nature, with simple configuration interaction (CI). To this end, we introduce the Wick theorem for nonorthogonal determinants, which enables an efficient implementation in conjunction with the direct CI scheme. The proposed approach, termed spin-extended CI with singles and doubles, achieves a balanced treatment between dynamic and static correlations. To approximately account for the quadruple excitations, we also modify the well-known Davidson correction. We report that our approaches yield surprisingly accurate potential curves for HF, H2O, N2, and a hydrogen lattice, compared to traditional single reference wave function methods at the same computational scaling as regular CI.

In sinus floor augmentation of an atrophic posterior maxilla, platelet-rich fibrin (PRF) has been used as a graft material. We herein report two cases with histological evaluations of PRF after the surgery. The first case was a 28-year-old female with an atrophic right posterior maxilla who was treated with sinus floor augmentation and simultaneous implant placement using PRF as the sole graft material in our hospital. Twenty-four months after surgery, the implant was unfortunately removed because of occlusal overloading by parafunctional habits. During implant replacement, a tissue sample was obtained from the site of augmentation with PRF and was evaluated histologically. The second case was a 58-year-old man with severe alveolar atrophy of the right maxilla who underwent lateral sinus augmentation using only PRF in a two-stage procedure in our hospital. Samples were obtained at the second-stage surgery and histological examinations were performed. As a result, new bone formation was confirmed histologically in both cases. Our findings show that the use of PRF as a graft material during sinus floor augmentation induces natural bone regeneration.

Spin-flip approaches capture static correlation with the same computational scaling as the ordinary single reference methods. Here, we extend spin-flip configuration interaction singles (SFCIS) by projecting out intrinsic spin-contamination to make it spin-complete, rather than by explicitly complementing it with spin-coupled configurations. We give a general formalism of spin-projection for SFCIS, applicable to any spin states. The proposed method is viewed as a natural unification of SFCIS and spin-projected CIS to achieve a better qualitative accuracy at a low computational cost. While our wave function ansatz is more compact than previously proposed spin-complete SF approaches, it successfully offers more general static correlation beyond biradicals without sacrificing good quantum numbers. It is also shown that our method is invariant with respect to open-shell orbital rotations, due to the uniqueness of spin-projection. We will report benchmark calculations to demonstrate its qualitative performance on strongly correlated systems, including conical intersections that appear both in ground-excited and excited-excited degeneracies.

Objective: Oral mucositis is a common adverse reaction to radiotherapy for head and neck cancer, and there are concerns regarding a decreased quality of life in patients receiving radiotherapy. The purpose of this study was to investigate the relationship between the severity of radiation-induced oral mucositis and the myeloperoxidase (MPO) levels in irradiated tissues., Study Design: Ninety-six F344 rats were divided into the following 4 groups: 10-Gy, 18-Gy, and 30-Gy irradiation groups, and a nonirradiation group. Oral mucositis was induced by the administration of single doses of radiation via exposure. After irradiation, the rats were evaluated on the basis of weight measurements, macroscopic findings according to a grading scale (Oral Mucositis Index [OMI]), and the results of tissue MPO assays., Results: Weights decreased whereas the OMI scores and MPO levels increased, depending on the dose of exposure. The Spearman rank correlation test showed a significant correlation between the OMI scores and the MPO levels in the tissues with a correlation coefficient of 0.824 (P < .01)., Conclusions: In this study, the MPO levels in the irradiated tissue were increased in the cases involving severe radiation-induced oral mucositis evaluated in rats using a grading scale., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Density matrix embedding theory (DMET) has emerged as a powerful tool for performing wave function-in-wave function embedding for strongly correlated systems. In traditional DMET, an accurate calculation is performed on a small impurity embedded in a mean field bath. Here, we extend the original DMET equations to account for correlation in the bath via an antisymmetrized geminal power (AGP) wave function. The resulting formalism has a number of advantages. First, it allows one to properly treat the weak correlation limit of independent pairs, which DMET is unable to do with a mean-field bath. Second, it associates a size extensive correlation energy with a given density matrix (for the models tested), which AGP by itself is incapable of providing. Third, it provides a reasonable description of charge redistribution in strongly correlated but non-periodic systems. Thus, AGP-DMET appears to be a good starting point for describing electron correlation in molecules, which are aperiodic and possess both strong and weak electron correlation.

Background: Most bone tumors that occur in the clavicle are malignant. A few giant cell tumors (GCTs) of the clavicle have been reported; however, the most appropriate operative method for this tumor has never been discussed., Case Presentation: A 54-year-old man noticed enlargement of the proximal aspect of the right clavicle. A plain X-ray revealed lytic change and ballooning of the proximal end of the right clavicle. The tumor was isointense on T1-weighted magnetic resonance images and showed a mixture of low- and high-intensity areas on T2-weighted images without extension to the surrounding soft tissues. Bone scintigraphy showed strong accumulation (normal/tumor ratio, 2.31), and positron emission tomography revealed strong uptake of fluorine-18-2-fluoro-2-deoxy-d-glucose (SUVmax, 6.0) in the proximal part of the right clavicle. Because we could not completely exclude malignancy, an open biopsy was performed. Pathologically, the tumor comprised mononuclear stromal cells and multinuclear giant cells, resulting in a diagnosis of a GCT of the bone. Although curettage may be considered for such lesions (Campanacci grade II), we chose resection to minimize the chance of recurrence. The tumor was resected en-bloc with the proximal half of the clavicle. No postoperative shoulder disproportion was observed, and full range of motion of the right shoulder was maintained. The patient was satisfied with the surgical outcome (Musculoskeletal Tumor Society score of 96 %). He returned to his original job as a land and house investigator without any signs of recurrence for 1 year after surgery., Conclusions: Although GCT of the bone rarely occurs in the clavicle, the typical X-ray findings demonstrated in the present case are helpful for a correct diagnosis. Although en-bloc resection without reconstruction is appropriate for GCTs in expendable bones, there has been much discussion about shoulder function after total claviculectomy. Considering the importance of the function of the clavicle, which is to support the scapula through the acromioclavicular joint, we preserved the muscle attachments of the deltoid, trapezius, and pectoralis major. Because both the oncological and functional outcomes were satisfactory, we recommend preservation of as much of the clavicle as possible in patients with clavicular bone tumors.

Projected Hartree-Fock (PHF) has recently emerged as an alternative approach to describing degenerate systems where static correlation is abundant, when the spin-symmetry is projected. Here, we derive a set of linearized time-dependent equations for PHF in order to be able to access excited states. The close connection of such linear-response time-dependent PHF (TDPHF) to the stability condition of a PHF wave function is discussed. Expanding this analysis also makes it possible to give analytical expressions for the projected coupling terms of Hamiltonian and overlaps between excited Slater determinants. TDPHF with spin-projection (TDSUHF) and its Tamm-Dancoff approximation are benchmarked for several electronically degenerate molecules including the dissociating H2, F2 and O3 at equilibrium, and the distorted ethylene. It is shown that they give consistently better descriptions of excited states than does time-dependent HF (TDHF). Furthermore, we demonstrate that they offer not only singly but also doubly excited states, which naturally arise upon spin-projection. We also address the thermodynamic limit of TDSUHF, using non-interacting He gas. While TDPHF singly excited states tend to converge to those of HF with the size of the system due to the lack of size-extensivity of PHF, doubly excited states remain reasonable even at the thermodynamic limit. We find that the overall performance of our method is systematically better than the regular TDHF in many cases at the same computational scaling.

Post-transplant ES, which is often resistant to therapies, has seldom been described. This report describes a case of ES after UBMT for RCC. A five-yr-old boy developed RCC with no evidence of monosomy 7. Because no matching family donors were available for SCT and immunosuppressive therapy was ineffective, UBMT was performed when he was six yr old. The conditioning regimen included TAI (3 Gy) and administration of FLU, CY, and rabbit antithymocyte globulin. The recovery of blood cells was good. He displayed grade II acute GVHD involving only the skin. ES developed on day 66, with positive results for Epstein-Barr virus DNA and HHV 6. Cytopenia was resolved with treatment with RTX, GCV, an escalated dose of steroids, high-dose gammaglobulin, and romiplostim. No relapse has occurred since discontinuing steroids on day 177 and romiplostim on day 268. Post-SCT ES after UBMT is rare, and the risk factors and therapies are unclear. Prospective analysis and collection of cases from multiple centers are required for clarification., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

We present a novel method that appropriately handles both dynamical and static electron correlations in a balanced manner, using a perturbation theory on a spin-extended Hartree-Fock (EHF) wave function reference. While EHF is a suitable candidate for degenerate systems where static correlation is ubiquitous, it is known that most of dynamical correlation is neglected in EHF. In this work, we derive a perturbative correction to a fully spin-projected self-consistent wave function based on second-order Møller-Plesset perturbation theory (MP2). The proposed method efficiently captures the ability of EHF to describe static correlation in degeneracy, combined with MP2's ability to treat dynamical correlation effects. We demonstrate drastic improvements on molecular ground state and excited state potential energy curves and singlet-triplet splitting energies over both EHF and MP2 with similar computational effort to the latter.

Water splitting by artificial catalysts is a critical process in the production of hydrogen gas as an alternative fuel. In this paper, we examine the essential role of theoretical calculations, with particular focus on density functional theory (DFT), in understanding the water-splitting reaction on these catalysts. First, we present an overview of DFT thermochemical calculations on water-splitting catalysts, addressing how these calculations are adapted to condensed phases and room temperature. We show how DFT-derived chemical descriptors of reactivity can be surprisingly good estimators for reactive trends in water-splitting catalysts. Using this concept, we recover trends for bulk catalysts using simple model complexes for at least the first-row transition-metal oxides. Then, using the CoPi cobalt oxide catalyst as a case study, we examine the usefulness of simulation for predicting the kinetics of water splitting. We demonstrate that the appropriate treatment of solvent effects is critical for computing accurate redox potentials with DFT, which, in turn, determine the rate-limiting steps and electrochemical overpotentials. Finally, we examine the ability of DFT to predict mechanism, using ruthenium complexes as a focal point for discussion. Our discussion is intended to provide an overview of the current strengths and weaknesses of the state-of-the-art DFT methodologies for condensed-phase molecular simulation involving transition metals and also to guide future experiments and computations toward the understanding and development of novel water-splitting catalysts.

The constrained density functional theory-configuration interaction (CDFT-CI) method has previously been used to calculate ground-state energies and barrier heights, and to describe electronic excited states, in particular conical intersections. However, the method has been limited to evaluating the electronic energy at just a single nuclear configuration, with the gradient of the energy being available only via finite difference. In this paper, we present analytic gradients of the CDFT-CI energy with respect to nuclear coordinates, which gives the potential for accurate geometry optimization and molecular dynamics on both the ground and excited electronic states, a realm which is currently quite challenging for electronic structure theory. We report the performance of CDFT-CI geometry optimization for representative reaction transition states as well as molecules in an excited state. The overall accuracy of CDFT-CI for computing barrier heights is essentially unchanged whether the energies are evaluated at geometries obtained from quadratic configuration-interaction singles and doubles (QCISD) or CDFT-CI, indicating that CDFT-CI produces very good reaction transition states. These results open up tantalizing possibilities for future work on excited states.

Objective: The aim of this study was to evaluate the healing effect of topically applied platelet-rich fibrin (PRF) on experimental oral mucositis induced by chemotherapy in hamsters., Study Design: Oral mucositis was induced in 93 Syrian golden hamsters by an intraperitoneal injection of 5-fluorouracil, which was followed by light scratching of the cheek pouch. The hamsters were randomly divided into a PRF group, a fibrin group, and an untreated control group. The recovery stage of oral mucositis was evaluated through daily weighing, measurements of the ulcer area, histopathologic analysis, and a myeloperoxidase activity assay., Results: The PRF group exhibited significant improvements in the size and histologic features of the ulcer and in the myeloperoxidase activity compared with the control group (P < .05)., Conclusions: The current findings suggest the consideration for future clinical trials in humans., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Restricted open-shell Kohn-Sham (ROKS) theory provides a powerful computational tool for calculating singlet excited state energies and dynamics. However, the possibility of multiple solutions to the ROKS equations - with the associated difficulty of automatically selecting the physically meaningful solution - limits its usefulness for intensive applications such as long-time Born-Oppenheimer molecular dynamics. We present an implementation of ROKS for excited states which prescribes the physically correct solution from an overlap criterion and guarantees that this solution is stationary, allowing for straightforward evaluation of nuclear gradients. The method is used to benchmark ROKS for vertical excitation energies of small and large organic dyes and for the calculation of Stokes shifts. With common density functional approximations, ROKS vertical excitation energies, and Stokes shifts show similar accuracy to those from time-dependent density functional theory and Δ-self-consistent-field approaches. Advantages of the ROKS approach for excited state structure and molecular dynamics are discussed.

The influence of the third molars on mandibular incisor crowding has been extensively studied but remains controversial. The purpose of this study was to ascertain whether, in Mongolian subjects, the lower third molar can affect anterior crowding and/or the inclination of teeth in the lower lateral segments. Panoramic radiographs, 45° oblique cephalograms, and dental casts were taken from Mongolian subjects (age range 18.3-24.1 years, mean 21.0 years) exhibiting impaction of all four third molars and an Angle Class I molar relationship. The Ganss ratio was calculated using panoramic radiographs, whereas the gonial angle and angulation of lower canines, premolars and molars were measured using 45° oblique cephalograms. Little's index of irregularity was calculated using dental casts. Significant relationships between the angulation of the third and second molars and between the first molars and second premolars were found. Conversely, there was no significant correlation between the angulation of third molars, first premolars and canines. The Ganss ratio calculations showed that the lower first and second molars and the second premolars inclined mesially if there was insufficient space for the lower third molars. However, there was no significant correlation between Little's index of irregularity and third molar angulation. Furthermore, although the third molar influences the lateral segments, no obvious relationship between the third molar and anterior crowding was observed. Therefore, the angulation of the third molar appears not to cause anterior crowding.

Projected Hartree-Fock (PHF) theory has a long history in quantum chemistry. PHF is here understood as the variational determination of an N-electron broken symmetry Slater determinant that minimizes the energy of a projected state with the correct quantum numbers. The method was actively pursued for several decades but seems to have been abandoned. We here derive and implement a "variation after projection" PHF theory using techniques different from those previously employed in quantum chemistry. Our PHF methodology has modest mean-field computational cost, yields relatively simple expressions, can be applied to both collinear and non-collinear spin cases, and can be used in conjunction with deliberate symmetry breaking and restoration of other molecular symmetries like complex conjugation and point group. We present several benchmark applications to dissociation curves and singlet-triplet energy splittings, showing that the resulting PHF wavefunctions are of high quality multireference character. We also provide numerical evidence that in the thermodynamic limit, the energy in PHF is not lower than that of broken-symmetry HF, a simple consequence of the lack of size consistency and extensivity of PHF.

Describing strong (also known as static) correlation caused by degenerate or nearly degenerate orbitals near the Fermi level remains a theoretical challenge, particularly in molecular systems. Constrained-pairing mean-field theory has been quite successful, capturing the effects of static correlation in bond formation and breaking in closed-shell molecular systems by using singlet electron entanglement to model static correlation at mean-field computational cost. This work extends the previous formalism to include triplet pairing. Additionally, a spin orbital extension of the "odd-electron" formalism is presented as a method for understanding electron entanglement in molecules.

We have recently proposed a novel approach for obtaining high-spin restricted open-shell Hartree-Fock wave functions by imposing constraints on the unrestricted Hartree-Fock (UHF) method [T. Tsuchimochi and G. E. Scuseria, J. Chem. Phys. 133, 141102 (2010)]. We here extend these ideas to the case where the constraints are released in an active space but imposed elsewhere. If the active space is properly chosen, our constrained UHF (CUHF) method greatly benefits from a controlled broken-symmetry effect while avoiding the massive spin contamination of traditional UHF. We also revisit and apply Löwdin's projection operator to CUHF and obtain multireference wave functions with moderate computational cost. We report singlet-triplet energy splittings showing that our constrained scheme outperforms fully unrestricted methods. This constrained approach can be readily used in spin density functional theory with similar favorable effects.

Restricted open-shell Hartree-Fock (ROHF) theory is formulated as a projected self-consistent unrestricted HF (UHF) model by mathematically constraining spin density eigenvalues. This constrained UHF (CUHF) wave function is identical to that obtained from Roothaan's effective Fock operator. The α and β CUHF Fock operators are parameter-free and have eigenvalues (orbital energies) that are physically meaningful as in UHF, except for eliminating spin contamination. This new way of solving ROHF leads to orbitals that turn out to be identical to semicanonical orbitals. The present approach removes ambiguities in ROHF orbital energies.

Our previously developed constrained-pairing mean-field theory (CPMFT) is shown to map onto an unrestricted Hartree-Fock (UHF) type method if one imposes a corresponding pair constraint to the correlation problem that forces occupation numbers to occur in pairs adding to one. In this new version, CPMFT has all the advantages of standard independent particle models (orbitals and orbital energies, to mention a few), yet unlike UHF, it can dissociate polyatomic molecules to the correct ground-state restricted open-shell Hartree-Fock atoms or fragments.

The recently proposed constrained-pairing mean-field theory (CPMFT) is here extended to include exchange and correlation effects from density functional theory (DFT) via alternative densities. We transform from alpha and beta spin densities to alternatives based on the total and on-top pair densities. This transformation is needed because CPMFT produces correct spin-symmetry and space-symmetry adapted densities that traditional DFT functionals are not designed to work with. The inclusion of DFT exchange and correlation effects in CPMFT is well founded both on practical and methodological reasons. We present multiple benchmarks showing that in many cases our model accurately reproduces unrestricted hybrid functional energies (both regular and range separated) and does so on the correct space-symmetry and spin-symmetry surface. Our approach affords efficient inclusion of dynamical correlation effects absent in CPMFT.

Our recently proposed constrained-pairing mean-field theory (CPMFT) is here extended to deal with dissociation of electron pairs to nondegenerate orbitals. To achieve this goal, we introduce the concept of asymptotic constraints. This extended CPMFT model can exactly dissociate polyatomic molecules to restricted open-shell atoms or fragments. We present benchmarks showing how CPMFT accounts for static correlation in an accurate yet computationally inexpensive mean-field manner, while preserving space and spin symmetries. The key element of our approach is the admittance of electron number fluctuations into the wave function.

We present a mean-field approach for accurately describing strong correlations via electron number fluctuations and pairings constrained to an active space. Electron number conservation is broken and correct only on average, but both spin and spatial symmetries are preserved. Optimized natural orbitals and occupations are determined by diagonalization of a mean-field Hamiltonian. This constrained-pairing mean-field theory (CPMFT) yields a two-particle density matrix ansatz that exclusively describes strong correlations. We demonstrate CPMFT accuracy with applications to the metal-insulator transition of large hydrogen clusters and molecular dissociation curves.

The Sakurai-Sugiura projection (SS) method was implemented and numerically assessed for diagonalization of the Hamiltonian in time-dependent density functional theory (TDDFT). Since the SS method can be used to specify the range in which the eigenvalues are computed, it may be an efficient tool for use with eigenvalues in a particular range. In this article, the SS method is applied to core excited calculations for which the eigenvalues are located within a particular range, since the eigenvalues are unique to atomic species in molecules. The numerical assessment of formaldehyde molecule by TDDFT with core-valence Becke's three-parameter exchange (B3) plus Lee-Yang-Parr (LYP) correlation (CV-B3LYP) functional demonstrates that the SS method can be used to selectively obtain highly accurate eigenvalues and eigenvectors. Thus, the SS method is a new and powerful alternative for calculating core-excitation energies without high computation costs., (2008 Wiley Periodicals, Inc.)

We describe two fatal cases of child abuse in which neighbors were unaware of the victims' disappearance for 1.5 months and 1 year, respectively. Recently, there have been fatal child abuse cases in which neighbors have been aware of the signs of the abuse but not notified the Child Care Authorities. Lack of concern about child welfare in the community is the greatest obstacle to protecting children at risk of abuse. The most effective means of preventing child abuse is to educate the community about how to recognize the signs of abuse and to inform the authorities. We emphasize that the community has an obligation to protect children against crime, including child abuse. The roles of the Social Services in preventing child abuse have been extended. Forensic pathologists are required to play a key role in child abuse prevention, and in Japan their activity should be extended to the administrative field.

Reported are 2 autopsy cases in which Y-chromosomal microsatellite short tandem repeats DYS19, DYS389I and II, DYS390, and DYS393 could be haplotyped with vaginal swabs by using a Chelex 100-based DNA extraction method and dual-round polymerase chain reaction. The extraction of DNA from vaginal swabs by using this method was as efficient or more efficient than using proteinase K and phenol-chloroform extraction or the alkaline lysis methods. Y-chromosomal microsatellite short tandem repeats haplotyping based on the dual-round polymerase chain reaction method provided genotypes from all the loci determined. Although amplification of Y-chromosomal microsatellite short tandem repeats loci is not directly involved in the existence of spermatozoa, it is considerably advantageous for male individualization from body fluid mixture stains in criminal cases.

On March 20, 1995, the Tokyo subway system was subjected to a horrifying terrorist attack with sarin gas (isopropyl methylphosphonofluoridate) that left 12 persons dead and over 5000 injured. In order to diagnose the definite cause of death of the victims, a new method was developed to detect sarin hydrolysis products in the erythrocytes and formalin-fixed cerebella from four victims of sarin poisoning. Sarin-bound acetylcholinesterase (AChE) was solubilized from the specimens of sarin victims and digested with trypsin. The sarin hydrolysis products bound to AChE were released by alkaline phosphatase digestion. The digested sarin hydrolysis products were subjected to trimethylsilyl derivatization and detected by gas chromatography-mass spectrometry. Sarin hydrolysis products were detected in all sarin poisoning victims.