Self-consistent generalized valence bond (GVB) and configuration-interaction calculations have been performed for a cluster model of the neutral vacancy in silicon. Three low-lying states ('E, 'T„sA2) are found to possess one electron in dangling-bond orbitals on each of the four silicon atoms around the defect. Of these three covalent states, the 'E is found to be the ground state with the exc...

The nondynamical correlation energy may be defined as the difference between full configuration interaction within the space of all valence orbitals and a single determinant of molecular orbitals ~Hartree–Fock theory!. In order to describe bond breaking, diradicals, and other electronic structure problems where Hartree–Fock theory fails, a reliable description of nondynamical correlation is ess...

Benzene is the emblematic example of an aromatic molecule, and the problem of its structure has given rise to a chemical serial story running over several decades. The epistemological digest of this story written by Stephen G. Brush1,2 shows how this problem has been at the root of important concepts such as those of mesomery and resonance. Before the advent of quantum mechanics, chemists had t...

Systematic variations of the bond-valence sums calculated from the poorly determined bond-valence parameters [Sidey (2008), Acta Cryst. B64, 515-518] have been illustrated using a simple graphical scheme.

The chemical bond overlap properties were obtained for alkali halides NaY (Y = F, Cl, Br), alkaline-earth chalcogenides MX (M = Ca, Mg and X = O, S, Se) and alkali and alkali-earth metals (Li, Na, and Mg) in diatomic and solid-state systems using an embedding approach based on the frozen density functional theory to simulate the crystalline effects. The computational protocol established provid...

In this article we present a multistate continuum theory for multiple charge transfer reactions such as proton-coupled electron transfer and multiple proton transfer reactions. The solute is described with a multistate valence bond model, the solvent is represented as a dielectric continuum, and the transferring protons are treated quantum mechanically. This theory provides adiabatic free energ...

The statistical resonating-valence-bond theory of metals is applied in the purely theoretical calculation of the composition of the Ni-Cu alloy at the foot of the curve of saturation ferromagnetic moment, which marks the boundary between hypoelectronic and hyperelectronic metals and determines the value of the number of metallic orbitals per atom. The results, Ni(44)Cu(56) and 0.722 metallic or...

BACKGROUND Many important geochemical and biogeochemical reactions occur in the mineral/formation water interface of the highly abundant mineral, goethite [α-Fe(OOH)]. Ab initio molecular dynamics (AIMD) simulations of the goethite α-FeOOH (100) surface and the structure, water bond formation and dynamics of water molecules in the mineral/aqueous interface are presented. Several exchange correl...

On the basis of the Gaussian vertical backscatter (GVB) model, this paper proposes a new method for extracting pine forest height and forest underlying digital elevation model (FUDEM) from multi-baseline (MB) P-band polarimetric-interferometric radar (PolInSAR) data. Considering the linear ground-to-volume relationship, the GVB is linked to the interferometric coherences of different polarizati...