Exact relations between the electron density and external potential for systems of interacting and noninteracting electrons

The differential virial theorem (DVT) is an explicit relation between the electron density ρ( r ), the external potential, kinetic energy density tensor, and (for interacting electrons) the pair function. The time‐dependent generalization of this relation also involves the paramagnetic current density. We present a detailed unified derivation of all known variants of the DVT starting from a modified equation of motion for the current density. To emphasize the practical significance of the theorem for noninteracting electrons, we cast it in a form best suited for recovering the Kohn–Sham effective potential v_s( r ) from a given electron density. The resulting expression contains only ρ( r ), v_s( r ), kinetic energy density, and a new orbital‐dependent ingredient containing only occupied Kohn–Sham orbitals. Other possible applications of the theorem are also briefly discussed. © 2012 Wiley Periodicals, Inc.     

Possible transformations of the ozone molecule in the presence of water associates

Possible channels of ozone transformations in the atmosphere in the presence of isolated water molecules or water associates were studied by quantum-chemical calculations of model systems comprising ozone and water molecules. The calculations were performed using the multiconfigurational self-consistent field approach in the complete active space, including perturbation theory corrections. The electronic excitation of the ozone molecule coordinated to a water associate should result in the formation of a strongly excited hydrogen peroxide molecule, which easily decomposes to two OH radicals. An alternative, less probable, transformation channel involves the formation of the HO₂ radical and atomic hydrogen. The interaction of the ozone molecule with the OH radical in turn results in the formation of the HO₂ radical and oxygen molecule. The MP2 variant of the one-configuration Möller-Plesset perturbation theory was shown to be inapplicable to describing the HO₄ system.     

The electronic structure and energetics of V(+)-benzene half-sandwiches of different multiplicities: Comparative multireference and single-reference theoretical study

Multireference [complete active space self-consistent field (CASSCF) and multiconfigurational quasidegenerate perturbation theory (MCQDPT)] and single-reference ab initio (Moller-Plesset second order perturbation theory (MP2) and coupled clusters with singles, doubles and noniterative triples [CCSD(T)]) and density functional theory (PBE and B3LYP) electronic structure calculations of V(C(6)H(6))(+) half-sandwich in the states of different multiplicities are described and compared. Detailed analyses of the geometries and electronic structures of the all found states are given; adiabatic and diabatic dissociation energies are estimated. The lowest electronic state of V(C(6)H(6))(+) half-sandwich was found to be the quintet (5)B(2) state with a slightly deformed upside-down-boat-shaped benzene ring and d(4) configuration of V atom, followed by a triplet (3)A(2) state lying about 4 kcal/mol above. The lowest singlet state (1)A(1)(d(4)) lies much ( approximately 28 kcal/mol) higher. MCQDPT calculated adiabatic dissociation energy (53.6 kcal/mol) for the lowest (5)B(2)(d(4)) state agrees well with the current 56.4 (54.4) kcal/mol experimental estimate, giving a preference to the lower one. Compared to MCQDPT, B3LYP hybrid exchange-correlation functional provides the best results, while CCSD(T) performs usually worse. Gradient-corrected PBE calculations tend to systematically overestimate metal-benzene binding in the row quintet相似文献   

Accurate explicitly correlated wave functions for two electrons in a square

An explicitly correlated linear-r(12) variational method is developed for a system of two electrons confined to a two-dimensional square well with infinite walls. The wave function is written as an expansion in products of non-negative integer powers of the relative and center-of-mass electronic coordinates and powers of r(12) restricted to 0 and 1. This form indirectly includes higher powers of the interelectronic distance and exhibits a much faster convergence than a similar expansion without r(12)-dependent terms. The method is implemented using high-precision floating-point arithmetic. Ground-state total energies are reported with at least 12 accurate significant figures for squares with sides from 1 to 50 bohrs. The method can be used "as is" for excited states and for two-dimensional rectangular wells. We also show that wave functions for two electrons in a square and in a rectangle have a higher symmetry than can be accounted for by the point group of the system.     

Interelectron magnetic coupling in electrides with one-dimensional cavity-channel geometry

Dye and coworkers [J. L. Dye, Acc. Chem. Res., 2009, 42, 1564] established experimentally that the strength of interelectron coupling in electrides with open intercavity channels critically depends on the channel diameter but is less sensitive to the channel length. We explain these observations by theoretical analysis of model electrides with a simple geometry. Our model consists of two electrons confined in a dogbone-shaped cavity--two spherical cages connected by a cylindrical channel. The coupling constant J is obtained from the calculated singlet-triplet gap of this system. By approximating the confining potential of the dogbone-shaped cavity with a one-dimensional double-well potential we show that ln(-J/k(B)), where k(B) is the Boltzmann constant, is a near-linear function of √((1/s) - (1/S)), where s and S are the cross-sectional areas of the channel and the cages, respectively. This prediction is in excellent agreement with the experiment for real electrides that have essentially one-dimensional cavity-channel networks.     

Orbital motion of dust particles in an rf magnetron discharge. Ion drag force or neutral atom wind force

Microparticles with sizes up to 130 μm have been confined and the velocity and diameter of particles in a plasma trap of an rf magnetron discharge with an arc magnetic field have been simultaneously measured. The motion of the gas induced by electron and ion cyclotron currents has been numerically simulated using the Navier-Stokes equation. The experimental and numerical results confirm the mechanism of the orbital motion of dust particles in the magnetron discharge plasma that is associated with the orbital motion of the neutral gas accelerated by electron and ion drift flows in crossed electric and magnetic fields.     

Nonempirical Description of the Atmospherically Important Anionic Species. II. Hydrated Ozone Anions

Ozone–water clusters are nonempirically modeled in the complete active space self-consistent field approximation (CASSCF) with the energetic estimates obtained at the multiconfiguration quasidegenerate perturbation theory level (MCQDPT) with 6–31++G** basis set. Coordination of a neutral ozone molecule to small water clusters is either surface or interior, with the binding energy of the order of a weak hydrogen bond. Upon localization of an excess electron, the hydration of ozone becomes strong. The adiabatic affinities of water–ozone clusters and the energies of electron detachment from their anions, depending on the number of water molecules, estimate the electron hydration and vertical electron detachment thresholds of water or ice that superficially coordinates minor amounts of ozone.