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Moisture is an important factor affecting the insulation properties of transformers. Due to the limitations of macroscopic experimental methods, the diffusion of water at oil–paper interface cannot...

It is difficult to overestimate how much quantum chemistry owes to Frank Boys. He was a pioneer, an individualist, a dedicated scientist and a great man.

The following collection of 25 papers has been submitted in honour of Professor Tim Softley, FRS to mark his 60th birthday. These papers tell us much about the man honoured in this special issue. T...

In this paper, we discuss the impact of using a frequency-dependent embedding potential in quantum chemical embedding calculations of response properties. We show that the introduction of a frequency-dependent embedding potential leads to further model complications upon solving the central equations defining specific molecular properties. On the other hand, we also show from a numerical point of view that the consequences of using such a frequency-dependent embedding potential is almost negligible. Thus, for the kind of systems and processes studied in this paper the general recommendation is to use frequency-independent embedding potentials since this leads to less complicated model issues. However, larger effects are expected if the absorption bands of the environment are closer to that of the region treated using quantum mechanics.

In this paper, we report vibrational energy levels of some tetraphenylporphyrins and its cation radicals, i.e. Cu[TPP], Cu[TPP]+, Ni(TPP), Ni(TPP)+, ClFe(TPP) and ClFe(TPP)+ using U(2) algebraic model Hamiltonian. In our study, we have used five fitting parameters which provide better comparisons between the experimental and theoretical calculations throughout the study. RMS deviation has been improved in this paper due to the inclusion of intermode couplings in algebraic model.Structure of metalloporphyrinsIn our work, we study the spectroscopic features of some biomolecules using Lie algebraic methods. This will be sought to be accomplished by studying the different vibrational energy levels as function of vibrational quantum numbers for certain biomolecules. Possibilities of local-to-normal transition in viable cases will be taken into consideration. In addition, new vibrational parameters for certain biomolecules will be sought to be identified for cases where Lie algebraic approach has not be...

In this paper, the effective interaction between charged colloids has been studied based on the standard Mayer function perturbation theory. With the formalism developed in this paper, the effective interaction as a function of Mayer functions and the correlation functions of the homogeneous microions is obtained. The asymptotic behaviour of the effective interaction at large distance is analysed in detail. It is found that at large distance the effective interaction is Yukawa like, provided the bare charge is replaced by the renormalised one. Exact expressions for the renormalised charge and the decay length as functions of the short-range part of the Mayer function and that of the correlation function of the homogeneous microions are obtained. With perturbation methods, it is easy to see how the effective interaction at large distance is affected by microion correlations and nonlinearity.

In a recent paper (J. Chem. Phys. 139, 064111, 2013), an antisymmetrised product of strongly orthogonal geminals with the expansion coefficients explicitly expressed by means of the occupation numbers was used to generate the Piris natural orbital functional 5 (PNOF5). This functional describes most of the non-dynamical effects, but also an important part of the intrapair (intrageminal) electron correlation. Second-order corrections to the generating PNOF5 wave function were derived using the multiconfigurational perturbation theory size consistent at the second order (SC2-MCPT) to include the missing interpair (intergeminal) electron correlation. A modified version of the SC2-MCPT involving double excitations only from different geminals was introduced and denoted as PNOF5-PT2. In this paper, the ground-state energies of 36 closed-shell species belonging to the G2/97 test set of molecules are studied by the PNOF5-PT2 and PNOF5-SC2-MCPT methods. The numerical performance of both methods on eight dimers, w...

In this paper, the Surrogate Hamiltonian approach is employed in order to study electronic relaxation in femtosecond laser-induced desorption experiments of CO from NiO(100). The study is based on ab initio calculations and a microscopic description of the NiO(100)-surface and the relaxation mechanism developed by Koch et al. The relaxation mechanism is assumed to be of dipole–dipole interaction nature, where the transition dipole moment of the adsorbate interacts with surface electron-hole pairs. In the Surrogate Hamiltonian approach the electron-hole pairs are treated as two-level systems and are described by excitation energy and a dipole charge. The Surrogate Hamiltonian parameters and potential energy surfaces used are obtained from ab initio calculations. The desorption probability and the velocity distributions of the desorbing molecules are calculated and an excited state lifetime is predicted. Throughout this paper atomic units, i.e. ℏ = m e = e = a 0 = 1, have been used unless otherwise stated.

To compute the rovibrational spectrum of a molecule undergoing large amplitude motion it is important to use geometrically defined internal coordinates. In this paper, we use polar-type coordinates and a contracted basis of products of vibrational wavefunctions and symmetric top functions: |v〉|JKM〉. To facilitate computing matrix elements of the kinetic energy operator obtained when the molecule-fixed axes are attached to two of the vectors used to define the coordinates, it is common to use vibrational basis functions that depend on K, the quantum number for the molecule-fixed z component of the angular momentum. In this paper, we show that it is possible to use a |v〉|JKM〉 basis and forgo the K-dependent primitive vibrational functions. Instead, we use a K-independent primitive basis that is an extension of the one employed in Mol. Phys. 110, 825, (2012) for triatomics. Using a K-independent primitive basis obviates the need to compute and store contracted vibrational bases for each K. First, we demonstr...

In a recent paper [B. Poirier, Chem. Phys. 370, 4 (2010)], a formulation of quantum mechanics was presented for which the usual wavefunction and Schrodinger equation are replaced with an ensemble of real-valued trajectories satisfying a principle of least action. It was found that the resultant quantum trajectories are those of Bohmian mechanics. In this paper, analogous ideas are applied to Bohmian Mechanics with Complex Action (BOMCA). The standard BOMCA trajectories as previously defined are found not to satisfy an action principle. However, an alternate set of complex equations of motion is derived that does exhibit this desirable property, and an approximate numerical implementation is presented. Exact analytical results are also presented, for Gaussian wavepacket propagation under quadratic potentials.

This paper supplements two papers by the same author [J. Chem. Phys. 134, 244308 and 224309, (2011)] devoted to the analysis of the experimental spectra of methyl radicals CH3O2 and CD3O2. It is devoted to the analysis of the lowest order terms of the rotational and of the centrifugal distortion Hamiltonian of molecules exhibiting an internal rotation (three-fold potential) or requiring a rotation of the reference frame with the perspective of determining the line intensity. It deals with different Hamiltonian expansions by keeping the uniqueness of the molecular parameters referenced in the principal-inertia-axis system (PAS) reference frame. The reduction of the effective second-order internal rotation Hamiltonian is discussed in the PAS and rho-axis-system (RAS) frames for application to standard (double-diagonalization) and new ‘non-approximate’ (single-diagonalization) approaches, i.e. PAM, RAM, SDPAM or SDRAM, which have been implemented to analyse the methyl peroxy radical spectra.

Phase separation, induced by attractive depletion interactions, in mixtures of two sizes of charged silica particles (30 and 200 nm diameter), dispersed in dimethylformamide (DMF), upon the addition of a non-adsorbing, monodispersed polymer (polystyrene) has been studied, for two polymer molecular weights (number-average 115,000 and 543,000). The repulsive electrostatic interaction between the silica particles was reduced through addition of 40 mM lithium chloride. This paper is a follow-up to a recent short communication by the same authors (J. Zhou, J. S. van Duijneveldt and B. Vincent, Phys. Chem. Chem. Phys. 13, 110–113 (2010)), for the same silica particles, plus the lower molecular weight polymer, in DMF. In that paper it was reported that, for certain concentration ranges of the ternary system, three co-existing phases are formed at equilibrium, and in others two. In this work it is shown that, despite the well-known importance of the polymer/colloid size ratio on the phase behaviour of their mixtu...

We consider a suspended elastic rod under longitudinal compression. The compression can be used to adjust potential energy for transverse displacements from harmonic to double well regime. As compressional strain is increased to the buckling instability, the frequency of fundamental vibrational mode drops continuously to zero (first buckling instability). As one tunes the separation between ends of a rod, the system remains stable beyond the instability and develops a double well potential for transverse motion. The two minima in potential energy curve describe two possible buckled states at a particular strain. From one buckled state it can go over to the other by thermal fluctuations or quantum tunnelling. Using a continuum approach and transition state theory (TST) one can calculate the rate of conversion from one state to other. Saddle point for the change from one state to other is the straight rod configuration. The rate, however, diverges at the second buckling instability. At this point, the straight rod configuration, which was a saddle till then, becomes hill top and two new saddles are generated. The new saddles have bent configurations and as rod goes through further instabilities, they remain stable and the rate calculated according to harmonic approximation around saddle point remains finite. In our earlier paper classical rate calculation including friction has been carried out [J. Comput. Theor. Nanosci. {\bf 4} (2007) {\it 1}], by assuming that each segment of the rod is coupled to its own collection of harmonic oscillators - our rate expression is well behaved through the second buckling instability. In this paper we have extended our method to calculate quantum rate using the same system plus reservoir model. We find that friction lowers the rate of conversion.

In previous papers we proved that the geometrical elements of the wave described by the Schrodinger equation, namely the wave surfaces and their normals, denoted by C curves, are solutions of the Hamilton–Jacobi equations, written for the same system, in the case of stationary systems. The C curves correspond to the same constants of motion as the eigenvalues of the Schrodinger equation. In two recent papers we presented a central field method for the calculation of the C curves, and of the corresponding energetic values. The method was verified for the atoms He, Li, Be, B, C, N and O. In this paper we extend this method, using the symmetry properties of the systems, in the case of the diatomic molecules, with exemplification for Li2, Be2, B2, C2, LiH, BeH, BH and CH. The accuracy of the method is, as in the case of the atoms, comparable to the accuracy of the Hartree–Fock method, for the same system. This could be a potential useful result, because our approach predicts also basic properties of the molec...

Active-space coupled-cluster (CC) methods, including their origin and recent developments, are reviewed, and further challenges in this area are briefly discussed. The focus is on the significance of the paper by Professors Stanislaw A. Kucharski and Rodney J. Bartlett, and the author of the present article [J. Chem. Phys. 110, 6103 (1999)], written when the author of the present article was a member of Professor Rodney J. Bartlett's research group at Quantum Theory Project. It is argued that that paper has played an important role in bringing the idea of selecting higher-than-double excitations within the single-reference CC framework to mimic multi-reference theories, proposed earlier [N. Oliphant and L. Adamowicz, J. Chem. Phys. 94, 1229 (1991); P. Piecuch et al., J. Chem. Phys. 99, 1875 (1993)], to the forefront of quantum chemistry development work, while inspiring extensions of such methods to electronically excited states and valence systems around closed shells via the equation-of-motion CC theory.

The present analysis improves previous measurements of self-broadening, self-shifting and self mixing of infrared ammonia in the wavenumber range 1000–1800 cm−1 at room temperature, based on spectra recorded using a high-resolution Fourier transform spectrometer Bruker IFS 120 HR. Previous studies in this spectral region catalogued numerous line-broadening, -shifting and -mixing. In the present paper, the corresponding spectroscopic parameters are obtained for 115 new lines in both ν4 and 2ν2 bands. The accuracies of self-broadening coefficients are about 3%. The mean accuracies of line-shifting and line-mixing data are estimated to be about 20% and 14%, respectively. As shown in a previous paper, the first-order Rosenkranz absorption coefficient taking into account line-mixing effects is adequate to extract with sufficient accuracy pressure-broadening as well as line-mixing and -shift parameters of self-perturbed NH3. Comparison of the results obtained with previous measurements and present theoretical c...

Algorithms useful in the construction of electron correlation models are collected alongside new developments for cases of high rank and sparsity. In the first part of this paper a Brandow diagram manipulation program is presented. The complementary second section describes a general-rank sparse contraction algorithm which exploits the permutational symmetries of many-fermion quantities. Several recently published local correlation models (perfect quadruples and perfect hextuples) were built using these codes. This paper should facilitate reproduction and extension of high-rank electron correlation models that combine truncation by level of substitution with truncation by locality, such as the number of entangled electron pairs.

This paper reports a molecular dynamics simulation study on the ionic dissociation of water. Experimentally the ionic product of water, KW , is known to exhibit an anomalous variation with temperature. It rises to a maximum at near-critical temperatures before falling off sharply as the temperature becomes super-critical. The paper describes a molecular dynamics simulation study, using the SPC/E water model, to gain insights into this surprising behaviour. Results for KW are in good agreement with experiment up to the critical point and the anomalous trend appears to be the result of a balance between the effects of a positive gas phase enthalpy of reaction, a decreasing electrostatic stabilisation of the ions with increasing temperature and more subtle entropic effects. The possibility of ion-pairing effects are considered and a simple estimate of the equilibrium dimerisation constants shows the dimer to be preferred at low temperatures, and the separated ions to be increasingly favoured at higher temper...

Organic light-emitting diodes (OLEDs) have been widely used in various fields such as sensors. In this article, we designed six novel heterocyclic Ir(III) complexes: (CFM)2Ir(acac) (named 1 in this paper), (TTIQ)2Ir(acac) (named 2), (CFM)2Ir(tmd) (named 3), (TTIQ)2Ir(tmd) (named 4), (CFM)2Ir(pic) (named 5) and (TTIQ)2Ir(pic) (named 6). The six iridium (III) complexes were calculated using Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT). We studied the bands of the lowest-lying absorptions and lowest energy emissions of complexes 1–6. In addition, we also explored their spectral properties, frontier Molecular Orbital theory(FMO) and spin-orbital coupling value(SOC). Where acac is represented as pentane-2, 4-dione; tmd as 2,2,6,6-tetramethylheptane-3,5-dione; pic as pyridine-2-carboxylate; TTIQ as 1-{thieno[3,2-b]thiophen-2-yl}isoquinoline; CFM as 2-(4-fluorobrobenyl)-4-methylpyridine. A series of heteroleptic cyclometalated Ir (III) complexes, which are used for OLED application, were investigated by DFT and TD-DFT method. The frontier molecular orbital character and charge transfer character shown that they have the advantages of low efficiency roll-off properties, which is a ‘stumbling block’ in the process of OLED solid-lighting’s development. Namely, means the materials will play an important role in the journey development of OLED.

This paper presents an overview of R-matrix theory of electron scattering by diatomic and polyatomic molecules. The paper commences with a detailed discussion of the fixed-nuclei approximation which in recent years has been used as the basis of the most accurate ab initio calculations. This discussion includes an overview of the computer codes which enable electron collisions with both diatomic and polyatomic molecules to be calculated. Nuclear motion including rotational and vibrational excitation and dissociation is then discussed. In non-resonant energy regions, or when the scattered electron energy is not close to thresholds, the adiabatic-nuclei approximation can be successfully used. However, when these conditions are not applicable, non-adiabatic R-matrix theory must be used and a detailed discussion of this theory is given. Finally, recent applications of the theory to treat electron scattering by polyatomic molecules are reviewed and a detailed comparison of R-matrix calculations and experimental measurements for water is presented.

This paper reports the excited quartet (S = 3/2) and quintet (S = 2) states arising from the intramolecular radical-triplet pair in the purely organic π conjugated spin systems. A previous paper reported the excited quartet and quintet states of 9-anthracene-(4-phenyliminonitroxide) and 9,10-anthracene-bis(4-phenyliminonitroxide), respectively, in which iminonitroxide radicals are linked to the phenyl- or diphenylanthracene moiety (a spin-coupler) through the π conjugation. The similar excited quartet and quintet states were observed for the 9-anthra-cene-(4-phenylverdazyl) radical (1) and 9,10-anthracene-bis(4-phenylverdazyl) diradical (2) by time resolved electron spin resonance (TRESR). The TRESR spectrum was analysed by the ordinary spin Hamiltonian with the Zeeman and fine structure terms. For the quartet state of 1, the g value, fine structure splitting, and relative population of the Ms sublevels have been determined to be g = 2.0035, D = 0.0230 cm−1, E = 0.0, P 1/2′ = P −1/2′ = 0.5 and P 3/2′ = P ...

This paper describes a collaboration between Professor Ernest Davidson and the author, which began in 1976 and lasted until Ernest left the University of Washington in 1984. During those 9 years we co-authored a total of 34 papers that described the results of ab initio calculations on a variety of different types of organic molecules, These included anti-aromatic annulenes, carbanions, carbenes, conjugated radicals and radical cations, and non-Kekle hydrocarbon diradicals. Our collaboration led to insights about symmetry breaking, both real and artefactual, which formed the basis for a frequently-cited review article on this subject that we co-authored. However, our most often-referenced paper was concerned with predicting the sizes and signs of the singlet-triplet splittings in diradicals, based on whether or not the non-bonding Huckel molecular orbitals of a diradical can be chosen so that they are confined to disjoint sets of atoms. In 1984, we co-authored a paper on the Cope rearrangement. Since then...

Thermally activated delayed fluorescence (TADF) molecules with dual emission have attracted extensive attention recently. However, the dual emission mechanism is complex and difficult to be studied especially in solid state. In this paper, asymmetrical diphenylketone derivatives CPzP and CPzPO are investigated in both benzene and in aggregation state with polarisable continuum model (PCM) and combined quantum mechanics and molecular mechanics (QM/MM) method respectively. It is found that there are both quasi-axial (ax) and quasi-equatorial (eq) conformations for CPzP and CPzPO in benzene. The ax conformation is responsible for the high energy band emission, while the low energy band emission is contributed by eq conformations. The dimers with intermolecular hydrogen bond have similar emission wavelengths with monomers. The small energy gap between the first singlet excited state and the first triplet excited state as well as large reverse intersystem crossing rate in eq conformations confirms the generation of TADF in eq conformation, which agree with experimental results that the low energy band emission is TADF. Our calculation results revealed the dual emission mechanism of two TADF molecules, which would favor the understanding of light emitting properties and the design of new type dual emission TADF emitters.

In a recent paper (Koehl, R. M., Odom, G. K., and Scuseria, G. E., 1996, Molec. Phys. 87, 835), we proposed a generalized version of the density matrix expansion of Negele and Vautherin. In the present paper, we have further modified this expansion by augmenting the second order term to explicitly include gradient corrections and correcting the Fermi momentum to account for the non-uniformity of the electron density. The resulting functional gives better results than the original exchange functional according to some preliminary hybrid calculations using Hartree–Fock densities for the G2 set of Pople and co-workers. While most of our investigations only concern closed shell molecules, we show that the results are easily generalized to the open shell case. The functionals thus obtained offer the possibility of improving the accuracy of existing exchange-correlation functionals.

This paper addresses the problem of finding the quantum bound-state energy eigenvalues and eigenvectors as functions of a set of continuous parameters characterizing a Hamiltonian. A recent paper introduced a parametric equations of motion (PEM) method for this purpose, and the present work extends the method to allow for the analysis ofa single energy level and its wavefunction. After solving the Schrodinger equation for its nth eigenvalue and eigenvector, evaluated at a reference value of the Hamiltonian's parameters, the differential equations of the single-state PEM (ss-PEM) method are used to propagate the nth energy level and its eigenfunction through the entire parameter space of the Hamiltonian. The new ss-PEM method, which reduces the number of differential equations to be solved, appears more efficient than diagonalization when the energy is sought at a moderate number of values for the parameters in the Hamiltonian. The PEM methods are extended to treat non-orthogonal basis sets that facilitate...

The response of a molecule to external electric fields can be described in terms of distributed polarizabilities. Such polarizabilities include both local and non-local effects. Methods of transforming the non-local polarizabilities into local ones are explored in this paper. Such transformations have to satisfy certain restrictions. The results for saturated and conjugated hydrocarbons suggest that full localization is not satisfactory, but that a scheme in which some charge-flow polarizabilities are retained gives values that are reasonably transferable between molecules. The paper also suggests how a transferable polarizability scheme may be developed for other kinds of molecules.

Photochemical reactions often involve states that are closely coupled due to near degeneracies, for example by proximity to conical intersections. Therefore, a multistate method is used to accurately describe these states; for example, ordinary perturbation theory is replaced by quasidegenerate perturbation theory. Multiconfiguration pair-density functional theory (MC-PDFT) provides an efficient way to approximate the full dynamical correlation energy of strongly correlated systems, and we recently proposed compressed multistate pair-density functional theory (CMS-PDFT) to treat closely coupled states. In the present paper, we report the implementation of analytic gradients for CMS-PDFT in both OpenMolcas and PySCF, and we illustrate the use of these gradients by applying the method to the excited states of formaldehyde and phenol.

In a recent paper (Molec. Phys. 1991, 73, 1183), Bramley et al. analysed the physical and mathematical context in which the vibrational rotational Hamiltonian operator for a molecule is expressed in terms of Euler angles for the rotation and internal curvilinear coordinates for the vibration. In the case of a generic tetra-atomic molecule, they derived a few rules which determine the choice of the basis functions, in order (i) to ensure continuity and single-valuedness of the eigenfunctions and (ii) to cancel out the singularities (infinite integrals) that unavoidably crop up in the matrix representation of the vibration-rotation kinetic energy operator. In another recent paper (Phys. Rev. A, 1992, 45, 6217), Chapuisat and lung considered the vibration-rotation of a polyatomic molecule as resulting from the rotational-vibrational motion of coupled relative vectors; with the help of a standard representation for the angular motion of each vector viewed in the moving frame resulting from the first two Euler rotations, i.e. for the whole molecule a direct product of spherical harmonics, they have shown that it is possible to get rid of the singularities and to derive, after completing the third Euler rotation, analytical expressions of the kinetic energy operator matrix elements in the usual bending-torsion-rotation basis. In implementing this approach, the rules derived for tetra-atomics by Bramley et al. are confirmed and are next generalized to the case of the N-atom molecule. The restrictions to the direct product representation which must be explicitly taken into account are established on the basis of a purely physical analysis of the coupled vector motion.

Laser-excited fluorescence and thermal emission spectra, recorded at high resolution by Fourier-transform spectrometry, have been analysed to yield new information about the ground-state, X2Σ+, and six of the lowest-lying electronic states of BaF. In the present paper we give values of the effective constants for X2Σ+, A′2Δ, A 2Π, B 2Σ+, C 2Π, D 2Σ+ and F 2Π derived from an overall simultaneous fit to some 6470 lines assigned to rotational structure of 24 bands of 10 systems. Existing analyses are confirmed and extended, and a rotational analysis of levels of the state C 2Π is given for the first time: the spin-orbit coupling constant in this state is found to increase unexpectedly rapidly with increasing v. The states A′2Δ, A 2Π and B 2Σ+ interact strongly, and their mutual deperturbation, and the determination of their interaction constants form the subject of the following paper (Part II).

Quasi-bound resonances of H$_2$ are produced via two-photon photolysis of H$_2$S molecules as reactive intermediates or transition states, and detected before decay of the parent molecule into three separate atoms. As was previously reported [K.F. Lai et al., Phys. Rev. Lett. 127, 183001 (2021)] four centrifugally bound quantum resonances with lifetimes of multiple $\mu$s, lying energetically above the dissociation limit of the electronic ground state X$^1\Sigma_g^+$ of H$_2$, were observed as X($v,J$) = (7,21)$^*$, (8,19)$^*$, (9,17)$^*$, and (10,15)$^*$, while also the short-lived ($\sim 1.5$ ns) quasi-bound resonance X(11,13)$^*$ was probed. The present paper gives a detailed account on the identification of the quasi-bound or shape resonances, based on laser detection via F-X two-photon transitions, and their strongly enhanced Franck-Condon factors due to the shifting of the wave function density to large internuclear separation. In addition, the assignment of the rotational quantum number is verified by subsequent multi-step laser excitation into autoionization continuum resonances. Existing frameworks of full-fledged ab initio computations for the bound region in H$_2$, including Born-Oppenheimer, adiabatic, non-adiabatic, relativistic and quantum-electrodynamic contributions, are extended into the energetic range above the dissociation energy. These comprehensive calculations are compared to the accurate measurements of energies of quasi-bound resonances, finding excellent agreement. Etc., Comment: Accepted Molecular Physics

This paper is the second of two back-to-back works, whose goal was to generate a more accurate linelist for the 5.8 µm absorption band of HNO3. Here, we report improved line positions and intensiti...

In this paper, Scarf II potential is used to construct the improved Scarf II potential energy function (ISPEF) for applications to diatomic molecules. Conditions to be satisfied by a diatomic molec...

This paper presents a unified model of gas phase acetone photophysics and photochemistry that is based on experimental data, which are reviewed and discussed in detail, and a detailed microcanonica...

The title of this Festschrift is intended to reflect threedicta that the jubilarian has invoked with collegiatespirit throughout his career, and has passed on to hisscientific progeny: ‘‘The difficult we do immediately.The impossible takes a little longer’’ (adopted from theSeabees [1]); ‘‘Ontogeny recapitulates phylogeny’’(amplified in Richard Dawkins’ masterpiece on evolu-tion, Climbing Mount Improbable [2]); and the‘‘scaling laws and form factors’’ (includingDimensional Scaling) that Dudley has discovered inhis scientific work and that have revealed so muchabout why things molecular – and other – are the waythey are. The title also implies Dudley’s fourth dictum,‘‘Keep going!’’ by which he has lived with anunmatched vigour and fortitude.This Festschrift, comprised of papers written inDudley Herschbach’s honour by his colleagues andformer students and associates, celebrates his distin-guished career. In addition, it offers a rich collectionof prefatory material, including an extensive interview,a list of Dudley’s students and coworkers, as well asthe Eighty Papers, a list of his own favouritepublications that he has compiled for this occasion.The full list can be found at Dudley’s website atHarvard [3] or at Texas A&M [4], along with twodefinitive reviews of his scientific work [5,6], essayson issues ranging from teaching to science funding,and much more – including some of his treasuredlecture notes. The prefatory section closes with DanKleppner’s essay on aspects of the well-known‘‘Herschbach effect.’’Richard Feynman once asked himself ‘‘If we couldpass on to posterity only one short sentence, whatshould it be?’’ His reply was ‘‘There really are atoms[7]’’. Although a fervent believer in the immensevalue of science, Dudley offered a different answer:‘‘The most important thing really is love!’’ And here iswhy: ‘‘With love comes awe, reverence, and compas-sion. With love, you know that whatever disappoint-ments or struggles lie behind or ahead, you are blessed.Beyond talent and energy, you can bring passion,vision, commitment to whatever you undertake. Youcan foster in yourself and others the awareness ofopportunity, the fellowship of striving, the joy ofdiscovery, the satisfactions of genuine service’’. And headded ‘‘So I’m glad to confess unabashedly my love formy life in science and the many wonderful people,ideas, and molecules that have come with it [8]’’.We, in turn, likewise confess a similar affection,and on this special occasion of his grand personalanniversary it is all directed towards the jubilarian:Happy birthday, Dudley!Bretislav Friedrich (Berlin)Sabre Kais (West Lafayette)David Mazziotti (Chicago)References

In this paper, we present a molecular dynamics study of the glass transition for a soft-core primitive model for ionic liquids, in which cations are fully flexible chains of tangent soft spherical ...