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Tuning center metal is an effective manner to modulate second-order NLO responses. When the big size Ir is introduced in complexes, the superior NLO responses can be found over its Rh counterparts.

A metal-free electrochemical method for vicinal difunctionalization of various alkenes with dibromomethane in alcohol as solvent has been well established to synthesize the corresponding β-bromo-α-alkyloxyalkanes with good functional group tolerance under ambient conditions. Preliminary mechanistic studies indicate the oxidation of bromine source occurs prior to that of alkene substrate with the involvement of bromine radical during electrolysis.

Block effective Hamiltonian theory (BEHT) is presented in this work. Configuration interaction functions are divided into

Polycyclic aromatic hydrocarbons (PAHs) are widely present in the environment as toxic pollutants. In this study, quantum chemistry methods are used to study reactions of PAHs in both particle and gas phases. Seven theoretical methods are exploited to predict the reactive sites of 15 PAHs in the particle phase. Among these methods, the performance of the condensed Fukui function (CFF) is optimum. The gas-phase reactions of eight PAHs are also investigated. Except for fluorene, CFF predicts correctly the gas-phase mono-nitro products for seven systems. The products of fluorene predicted by CFF are 1-nitrofluorene and 3-nitrofluorene, which is however inconsistent with the experimental results. Transition state theory is then used to investigate the reaction mechanism of fluorene. Calculated rate constants for 3-nitrofluorene and 2-nitrofluorene formation are much bigger than that for 1-nitrofluorene formation, which is in agreement with the experimental results.

A new equation related to the surface tension and concentration of solute in the surface region is derived and a three-step procedure is proposed to determine the molecular area of surfactants in aqueous solution at saturation of the air-liquid surface. Based on their surface tension data, the molecular areas of hexyl, octyl and decyl trimethylammonium bromide (HTABr, OTABr and DTABr) in aqueous solutions have been calculated and are in agreement with the computational results of density functional theory. Gibbs analysis has also been carried out for these surfactants. As the surface tension data are fitted with the Gibbs equation, it is found that there exist two line segments for both OTABr and DTABr, which lead to two molecular areas for each of them. This arbitrariness indicates that no unique molecular area could be obtained for OTABr and DTABr. As for HTABr, its molecular area obtained with Gibbs analysis is out of the range estimated with density functional theory. These results show the failure of the Gibbs equation.

Fabricating functional materials via molecular self-assembly is a promising approach, and precisely controlling the molecular building blocks of nanostructures in the self-assembly process is an essential and challenging task. Blue phase liquid crystals are fascinating self-assembled three-dimensional nanomaterials because of their potential information displays and tuneable photonic applications. However, one of the main obstacles to their applications is their narrow temperature range of a few degrees centigrade, although many prior studies have broadened it to tens via molecular design. In this work, a series of tailored uniaxial rodlike mesogens disfavouring the formation of blue phases are introduced into a blue phase system comprising biaxial dimeric mesogens, a blue phase is observed continuously over a temperature range of 280 °C, and the range remains over 132.0 °C after excluding the frozen glassy state. The findings show that the molecular synergistic self-assembly behavior of biaxial and uniaxial mesogens may play a crucial role in achieving the ultrastable three-dimensional nanostructure of blue phases., Blue phases are spatially ordered yet fragile liquid crystalline structures, bearing applications in optoelectronics and photonics. Hu et al. show that self-assembly within a mixture of different mesogens may significantly broaden the temperature range over which they are stable.

In this work, a bistable polymer framework liquid crystal (PFLC) thin film by thermal curing of epoxy monomers with two different thiols, a traditional flexible-structure thiol and a novel original rigid-structure thiol, has been successfully fabricated, combining a novel mixed morphology of polymer matrix and cholesteric liquid crystals with negative dielectric anisotropy. The polymer framework morphology has been formed by curing two types of epoxy monomers with two types of thiols, and the liquid crystals tend to be focal conic textures with large size domains at the initial state in the PFLC film so that it has a moderate light transmissivity at this state between the transparent state and the opaque state. Thus, the devices based on PFLC films can be switched reversibly between the transparent state and the opaque state by alternative electric field. In addition, the states can be sustained after the electric field is removed. The bistable memory effect comes from the anchoring effects of the polymer frameworks with a novel morphology in the microdomains of the PFLCs. Therefore, the optimized bistable PFLC film keeps its initial state without external electric field and any other energy consumption for a long time after altering the state by applying an instant electric field. The special polymer frameworks in the bistable PFLC films endow the films with excellent electro-optical properties and mechanical properties. The devices are energy-efficient and cost-saving and have great potential applications in energy-efficient reflective displays, electronic papers, writing tablets, and smart windows.

Morphologies of polymer networks are playing a key role in affecting the electro-optical (E-O) properties of a polymer dispersed liquid crystals (PDLCs) material. In this paper, the relationships between the polymer morphologies and the E-O properties of PDLCs are investigated in an unexplored thermally curing system based on epoxy/low-molar-mass-mercaptan. The polymer morphologies in this curing system can be regulated from polymer beads to porous polymer matrix by varying the liquid crystals (LCs) contents, chemical structures of epoxy monomers, and functionality of thiol hardeners. Interestingly, great improvements of E-O properties occur as the polymer structures change from polymer beads to porous frameworks, even though with an abnormal low LCs contents. Eventually, the mechanism for the formation of different polymer structures are illustrated and the relationships between the E-O properties and polymer structures are established. This work provides new insights in morphology control and optimizing the E-O properties in thermally cured PDLCs films.

Surface tension is one of the most important properties of liquid. A new theory is proposed and applied to the phenomena related to the surface tension of pure liquid compounds and strong electrolyte solutions. We first found that the phase transitions of pure liquid compounds from bulk to surface are exothermic and transition heats of 38 liquid compounds are determined quantitatively. This theory also describes successfully the variations of the surface tensions with the concentrations of solutes in strong electrolyte solutions. As a byproduct, minimum thicknesses of the surface layers of these solutions are deduced.

A series of sticky superhydrophobicity surfaces with high water contact angle and high water adhesive force is facilely prepared via an all-solution-processed method based on polymerization-induced phase separation between liquid crystals (LCs) and epoxy resin, which produces layers of epoxy microspheres (EMSs) with nanofolds on the surface of a substrate. The morphologies and size distributions of EMSs are confirmed by scanning electron microscopy. Results reveal that the obtained EMS coated-surface exhibits high apparent contact angle of 152.0° and high water adhesive force up to 117.6 μN. By varying the composition of the sample or preparing conditions, the sizes of the produced EMSs can be artificially regulated and, thus, control the wetting properties and water adhesive behaviors. Also, the sticky superhydrophobic surface exhibits excellent chemical stability, as well as long-term durability. Water droplet transportation experiments further prove that the as-made surface can be effectively used as a mechanical hand for water transportation applications. Based on this, it is believed that the simple method proposed in this paper will pave a new way for producing a sticky superhydrophobic surface and obtain a wide range of use.

Based on the complete active space multireference wavefunction, multireference Rayleigh-Schrodinger perturbation theory (MRSPT) is derived with the assumption that the orbital energies of active orbitals are the same as e¯, an unknown parameter. In this work, e¯ is optimized at the MRSPT2 level. The second and third order perturbation theories are shown numerically to be size extensive. The second order perturbation theory is exploited to compute the ground state energies of F2, AlH, HCl, and P2 and to optimize the equilibrium bond lengths and harmonic vibrational frequencies of BH, BF, P2, HF, and F2. The dissociation behaviors of NH3 and OH- have also been investigated. Comparisons with other theoretical models as well as the experimental data have been made to show advantages of the present theory.

Thiols are prone to react with a multitude of various functional groups in high yields, which has been widely used for surface- and particle-patterning, bioorganic synthesis, polymer modification, imprint nanolithography, the fabrication of optical components, hydrogel synthesis, and the curing of hard protective coatings. In this work, a chiral thiol with a high helical twisting power was synthesized through a novel synthetic route with high selectivity, yield, and cost-effectiveness. It was then used to fabricate a liquid-crystal composite film with ultra-wide broadband reflection via thiol click chemistry. Cholesteric liquid-crystal materials with broadband reflection have many potential applications for broadband polarizers, polarizer-free displays, organic optical data storage media, smart switchable reflective windows, and continuous waveband laser protection.

Predicting the reactivity of nucleophilic reaction at different sites has important theoretical and practical significance. Many prediction methods solely based on the electronic structure of reactants have been proposed. In this paper, detailed comparative analyses on the reliability of 14 methods are carried out and three series of molecules, carbonyl compounds, aromatic hydrocarbons and pyridine derivatives are exploited as test systems. It is found that the methods reflecting local electronic softness, such as condensed dual descriptor, have satisfactory prediction ability; while the ones reflecting electrostatic effect, such as atomic charge analysis and electrostatic potential analysis, have evidently worse overall performance. For all systems of interest, condensed dual descriptor and Hirshfeld charge display the most robust predictive capacity.

A new multireference perturbation series is derived based on the Rayleigh-Schrödinger perturbation theory. It is orbitally invariant. Its computational cost is comparable to the single reference Møller-Plesset perturbation theory. It is demonstrated numerically that the present multireference second- and third-order energies are size extensive by two types of supermolecules composed of H2 and BH monomers. Spectroscopic constants of F2(X1Σg+),Cl2(X1Σg+),C2-(X2Σg+),B2(X3Σg-),and C2+(X4Σg-) as well as the ground state energies of H2O, NH2, and CH2 at three bond lengths have been calculated with the second multireference perturbation theory. The dissociation behaviors of CH4 and HF have also been investigated. Comparisons with other approximate theoretical models as well as the experimental data have been carried out to show their relative performances.

Understanding the nature of noncovalent interactions between nonpolar small molecules is not only theoretically interesting but also important for practical purposes. The interaction mechanism of three prototype dimers (H2)2, (N2)2, and (H2)(N2) are investigated by state-of-the-art quantum chemistry calculations and energy decomposition analysis. It is shown that their configuration preferences are essentially controlled by the electrostatic component rather than the dispersion effect though the monomers have zero dipole moment. These configuration preferences can also be fairly well and conveniently interpreted by visually examining the electrostatic potential map.

Bond order is an important concept for understanding the nature of a chemical bond. In this work, we propose a novel definition of bond order, called the Laplacian bond order (LBO), which is defined as a scaled integral of negative parts of the Laplacian of electron density in fuzzy overlap space. Many remarkable features of LBO are exemplified by numerous structurally diverse molecules. It is shown that LBO has a direct correlation with the bond polarity, the bond dissociation energy, and the bond vibrational frequency. The dissociation behavior of LBO of the N-N bond in N2 has been studied. Effects of the basis sets, theoretic methods, and geometrical conformations on LBO have also been investigated. Through comparisons, we discussed in details similarities and discrepancies among LBO, Mayer bond order, natural localized molecular orbital bond order, fuzzy overlap population, and electron density at bond critical points.

Charge preservation is a necessary condition in population analysis. However, one such constraint is not enough to solve the arbitrariness involved in the population analysis such as Hirshfeld population. This arbitrariness results in too small Hirshfeld charges and poor reproducibility of molecular dipolar moments. In this article, the preservation of the molecular dipole moment is imposed upon the Hirshfeld population analysis as another constraint to improve the original Hirshfeld charges. In the scheme each atomic dipolar moment defined by the deformation density is expanded as contributions from all atoms in the molecule. The corresponding correction charges are then accumulated for each atom together with the original Hirshfeld charge as the predicted charge. All computed charges are generally larger than Hirshfeld charges, independent of basis set, and have very good electrostatic potential reproducibility and high correlation with the charges derived from the electrostatic potential fitting.

A few open-shell molecules are taken as examples in order to examine the performance of the open-shell perturbation theory for electron correlation (J Chem Theory Comput, 2009, 5: 931–936). The convergence of the perturbation series is shown to be stable for the doublet state of NH2 at both the equilibrium and stretched geometries. The equilibrium bond lengths, and harmonic and anharmonic vibrational frequencies are calculated for NO(X 2Π), OH(X 2Π), CH(X 2Π) and NH(X 2Σ−) with different second-order perturbation theories at the cc-pVDZ, cc-pVTZ and cc-pVQZ levels. The ground state energies of BeF(X 2Σ+), MgH(X 2Σ+) and the HCCl triplet state have also been computed with various perturbation theories and compared with configuration interaction with single and double excitations (CISD) and CISD + Davidson correction. The energy difference between the formaldehyde (H2CO+) and hydroxymethylene (HCOH+) radical cations has been computed. Our perturbation theory predicts correctly that H2CO+ is more stable than HCOH+. However, calculations using UMP2, CASPT2, the Z-averaged perturbation theory and restricted Moller-Plesset theory fail even to produce the correct sign of the energy difference.

Applications of the multireference linearized coupled-cluster single-doubles (MRLCCSD) to atomic and molecular systems have been carried out. MRLCCSD is exploited to calculate the ground-state energies of HF, H2O, NH3, CH4, N2, BF, and C2with basis sets, cc-pVDZ, cc-pVTZ and cc-pVQZ. The equilibrium bond lengths and vibration frequencies of HF, HCl, Li2, LiH, LiF, LiBr, BH, and AlF are computed with MRLCCSD and compared with the experimental data. The electron affinities of F and CH as well as the proton affinities of H2O and NH3are also calculated with MRLCCSD. These results are compared with the results produced with second-order perturbation theory, linearized coupled-cluster doubles (LCCD), coupled-cluster doubles (CCD), coupled-cluster singles and doubles (CCSD), CCSD with perturbative triples correction (CCSD(T)). It is shown that all results obtained with MRLCCSD are reliable and accurate.

A new single reference perturbation partition is proposed for restricted open-shell Hartree-Fock (ROHF) and complete active space self-consistent field (CASSCF) orbitals. It is a sum of one-particle operator which is implicitly defined. When the operator acts on a ROHF or CASSCF orbital, the resultant eigenvalue is the orbital's corresponding orbital energy coming from the ROHF or CASSCF calculation. HF, F2, and N2 with stretched bonds are used for the size extensivity test. Results indicate that the first three-order energies calculated with the new partition are size extensive. Single reference perturbation calculations for H2O, NH3, and CH4 with CASSCF orbitals have been performed and compared with other methods like MRCI, MRCI+Q, MRPT2, and MRPT3. The single reference nature of the present perturbation theory is also shown with computations of the singlet-triplet separation of the CH2 and SiH2 radicals.

The effectiveness of the approach for systematical reconstruction of higher order reduced density matrices with lower order ones, which was developed by Chen ( Science in China B , 2006, 49 : 402), was compared theoretically with that of Mazziotti's method through Harris model, by omitting the cumulant terms 3 Δ M , 4Δ M in the latter method and the normal product terms 3 Δ, 4 Δ in the former method, it was found that the errors from both approaches were comparable. As a better approximation, if only fourth-order terms 4Δ M and 4 Δ in both methods are neglected whereas the third-order terms 3Δ M and 3 Δ are computed from their cor-responding fourth-order terms 4Δ M and 4 Δ, respectively, through contractions, the results calculated with Chen's approach not only have the correct signs but also are very close to the exact normal products 3 Δ whereas some of the results calculated with Mazziotti's method do not even have the correct signs with respect to the exact cumulants 3Δ M .

Photoabsorption cross-sections of water dimer and trimer anions are calculated with an ab initio molecular orbital method. Because the electron detachment energy of these small water cluster anions is less than 0.3 eV, all of the photoabsorption spectra in the near-infrared and visible region are due to the bound-free transitions. The theoretical spectra of two isomers of dimer anion and three isomers of trimer anion are compared, which suggest the possibility of the identification of the isomer structure by the photoabsorption spectra. The convergence on the basis sets is also examined by adding diffuse functions.

Improvements in boundary element methods are described for solution of reaction field equations that incorporate important dielectric effects of solvation, including influences of volume polarization, into electronic structure calculations on solute properties. Most current implementations assume constant boundary elements on the cavity surface separating solvent from solute, often employing an empirical parameter to enhance slow convergence associated with the treatment of singularities. In this work we describe a scheme for the linear interpolation of boundary elements and the analytic treatment of singularities that improves convergence without the need for any empirical parameter. Another advance is described for isodensity surface triangulation that succeeds even with molecular surfaces having prominent pockets, which cause the failure of previous simpler methods. Numerical examples are presented to demonstrate the efficacy of these new procedures in practice.

In this Letter, a case is reported where a small basis set superposition error (BSSE) dependence on the geometry leads to a large change in the optimized structure. The rotational potential energy curves of the p -difluorobenzene–N 2 ( p -DFB–N 2 ) complex were calculated with MP2, MP3, MP4(SDQ) and basis sets at different levels. For all calculations with the BSSE correction, similar rotational potential curves and the same minimum point were obtained. On the other hand, the uncorrected potential curves were quite different from the above ones and from each other.

Electronic spectra of ammoniated ammonium radicals, NH4(NH3)n, produced through the photolysis of ammonia clusters, are investigated with a laser photodepletion spectroscopy. Vibrationaly resolved bands beginning at energy of 9305 ± 15 cm-1 are successfully assigned to NH4NH3. These bands are ascribed to the 2 2A −1 2A transition derived from the 3p 2F2−3s 2A1 excitation of NH4. A second group of bands beginning at energy 10073 ± 15 cm-1 is assigned to the 12E−12A transition. Electronic spectra of a series of NH4(NH3)n (n = 1−8) are also recorded with low resolution in the energy region of 4500−16000 cm-1. A drastic decrease of the excitation energy from 15062 cm-1 for NH4 to 5800 cm-1 for NH4(NH3)4 is observed, while no appreciable spectral change is found for n ≥ 5. The large spectral change is ascribed to the spontaneous ionization of NH4 in ammonia clusters. Successive binding energies of NH4(NH3)n in the excited state are determined from the spectral band positions.

A new time-independent perturbation theory is developed for the multireference problem. In the derivation, neither perturbed wave function nor intermediate normalization condition is required. In the single-reference case, the present approach gives the same perturbation expressions as Rayleigh-Schrodinger perturbation theory. In the multireference case, the perturbation expressions are derived with two kinds of partitions and can be applied to those cases with or without the definition of the zeroth Hamiltonian H 0 . As the size of the reference space is decreased to 1, one multireference expansion returns to the single-reference one with Epstein-Nesbet partition, while another is reduced to a new expansion. These two multireference perturbation expansions are further expressed with the eigenvectors of the Hamiltonian within the reference space for an efficient implementation. The correspondences between the single-reference and multireference perturbation expansion are discussed.

The geometrical structures of NH4 and OH3 were optimized at the MP2 level with the aug-cc-pvdz, aug-cc-pvtz, and aug-cc-pvqz basis set plus s-type diffuse functions. The adiabatic ionization potential, barrier height, and dissociation energy of NH4 and OH3 were calculated with the above basis set series and were extrapolated to the infinite basis set limit. The theoretical ionization potential of NH4 was in very good agreement with the experimental value. The N−H bond lengths of NH4 and NH4+ at the infinite basis set limit were obtained by parabolic interpolation around the equilibrium point. FH2 was optimized at the UHF, B3LYP, and MP2 levels. However, only a dissociated ground state was found. The potential energy curves for dissociation of the above molecules were calculated with MP2. The relative stabilities of these molecules and their isotopic counterparts are discussed. Theoretical hyperfine calculations were performed in the gas phase as well as in a neon matrix for NH4 and OH3 with a single-refer...

Ab initio calculations have been performed to interpret the photoelectron spectrum of gaseous cuprous chloride, Cu3Cl3. Density functional calculations revealed Cu3Cl3 to be a planar cyclic D3h molecule. Koopmans' theorem and two-hole/one-particle calculations with canonical Hartree-Fock orbitals were used to interpret the vertical ionization energies. These were compared with similar calculations using B3LYP Kohn-Sham orbitals. The results confirm the claim by Casida that Kohn-Sham orbitals mimic Dyson orbitals.

The structure of the CH2OH radical was optimized at the UHF, UB3LYP, and MP2 levels. The calculated ionization potential was very close to the experimental one. The transition dipole moments from the ground state to the first four lowest excited states were calculated with and without Cs symmetry using the multireference single and double configuration interaction method (MRSD). The first four lowest excited states were also optimized with the single excitation configuration interaction method (CIS). The adiabatic excitation energies and transition dipole moments for vertical emission were calculated at the same level. None of these calculations lead to the assignment of the first excited Rydberg p state as 2A‘ ‘(3pz) as suggested in a recent paper (Chem. Phys. Lett. 318, 393, 2000). Some results of multireference perturbation theory are also presented. The isotropic hyperfine parameters calculated with MRSD were in good agreement with the experimental values.

The electronic structure of the whole molecule of acidic phospholipase A2 (PLA2) from the venom of Agkistrodon halys pallas (A. halys pallas) has been calculated using the extended negative factor counting (ENFC) method in which dimers were calculated at the ab initio level using a minimal basis set, with simulation of the aqueous environment. Hopping conductivities were determined by the use of random walk theory. The results show that the frontier orbitals are mainly localized to residues which are involved in the biological activity of acidic PLA2. The C-terminal region might play some important role in biological activity because of its active electrons. The aromatic patch on the surface of the enzyme, together with two neighbouring acidic residues, has very active electrons that may be responsible for the inhibition of platelet aggregation. Trp30, which is involved in the interfacial recognition region, may transfer its electrons to the aggregated substrate. It is also concluded that the conductivity of the protein is caused mainly by holes transported through the valence band rather than electrons transferred in the conductive band. The a.c. conductivity of acidic PLA2 confirms that proteins, if doped, are amorphous conductors. Moreover, the a.c. conductivities of acidic PLA2 are approximately one order of magnitude higher than those of some other proteins. This suggests that the toxicity of acidic PLA2 may be related to its high a.c. conductivity.

Quantitative analysis of molecular surface is a valuable technique for analyzing non-covalent interaction, studying molecular recognition mode, predicting reactive site and reactivity. An efficient way to realize the analysis was first proposed by Bulat et al. (J. Mol. Model., 16, 1679), in which Marching Tetrahedra (MT) approach commonly used in computer graphics is employed to generate vertices on molecular surface. However, it has been found that the computations of the electrostatic potential in the MT vertices are very expensive and some artificial surface extremes will be presented due to the uneven distribution of MT vertices. In this article, we propose a simple and reliable method to eliminate these unreasonably distributed surface vertices generated in the original MT. This treatment can save more than 60% of total analysis time of electrostatic potential, yet the loss in accuracy is almost negligible. The artificial surface extremes are also largely avoided as a byproduct of this algorithm. In addition, the bisection iteration procedure has been exploited to improve accuracy of linear interpolation in MT. The most appropriate grid spacing for surface analysis has also been investigated. 0.25 and 0.20 bohr are recommended to be used for surface analysis of electrostatic potential and average local ionization energy, respectively.

Multiwfn is a multifunctional program for wavefunction analysis. Its main functions are: (1) Calculating and visualizing real space function, such as electrostatic potential and electron localization function at point, in a line, in a plane or in a spatial scope. (2) Population analysis. (3) Bond order analysis. (4) Orbital composition analysis. (5) Plot density-of-states and spectrum. (6) Topology analysis for electron density. Some other useful utilities involved in quantum chemistry studies are also provided. The built-in graph module enables the results of wavefunction analysis to be plotted directly or exported to high-quality graphic file. The program interface is very user-friendly and suitable for both research and teaching purpose. The code of Multiwfn is substantially optimized and parallelized. Its efficiency is demonstrated to be significantly higher than related programs with the same functions. Five practical examples involving a wide variety of systems and analysis methods are given to illustrate the usefulness of Multiwfn. The program is free of charge and open-source. Its precompiled file and source codes are available from http://multiwfn.codeplex.com.

BiVO4/TiO2 composite photocatalysts were successfully synthesised via different methods, and the physical and photophysical properties of the as-prepared photocatalysts were fully characterised by X-ray diffraction, scanning electron microscopy, field-emission transmission electron microscopy, energy dispersive spectroscopy, UV-vis diffuse reflectance spectroscopy, photoluminescence spectroscopy and Brunauer–Emmett–Teller (BET) surface area analysis. Methylene blue was selected as model pollutant to investigate the photocatalytic activity of BiVO4/TiO2 composite materials. The results reveal that BiVO4/TiO2 fabricated by different methods exhibits higher photocatalytic activity than pure BiVO4 and TiO2, and the coprecipitated BiVO4/TiO2 composite shows the best photocatalytic activity. The diffuse reflectance spectroscopy results demonstrated that the 20 wt-% coprecipitated BiVO4/TiO2 exhibited a significant, broad spectrum response not only between 400 and 500 nm but also from 500 to 800 nm wavelength.

Electronic structure calculations on ions that use dielectric continuum theory to mimic solvent around the bare ionic solutes are often prone to make large errors in the hydration energies. It is found for cations that much of the error can be accounted for by a simple linear correlation with the maximum value found anywhere on the dielectric cavity surface of the solute potential or, even better, the outgoing normal electric field, thus mirroring analogous results previously obtained for anions. This correlation allows for significantly improved estimates of cation hydration energies while still retaining cavities of physically reasonable size in determination of the bulk dielectric contributions.