Results of ab initio Hartree-Fock calculations for the SrTiO3 ~110! polar surface are discussed. We have calculated the surface energies, near-surface atomic displacements for four possible terminations ~TiO, Sr, and two kinds of O terminations! as well as Mulliken atomic charges and dipole moments of atoms characterizing their polarization, and the atomic bond populations. We predict a conside...

In this communication, we describe p-xylene oxidation with molecular oxygen at 373 K and atmospheric pressure using N-hydroximide catalysts. p-Xylene conversion was rather high over the first 2 h of reaction and complete by the end of the experiment. The product distribution curves versus reaction time are typical of consecutive reactions. The main intermediate product is p-toluic acid. Peak co...

A previous theory of separation of motions of core and valence fractions of electrons in a molecule [J. R. Mohallem et al., Chem. Phys. Lett. 501, 575 (2011)] is invoked as basis for the useful concept of Atoms-in-Molecules (AIM) in the stockholder scheme. The output is a new tool for the analysis of the chemical bond that identifies core and valence electron density fractions (core-valence sto...

Rajasekharan and Girgis reported that binary systems with intermetallic compounds of a particular crystal structure form a straight line on a map using Miedema’s parameters. In this paper, the universality of that observation is examined. Observations from a study of 143 binary systems that crystallize in six different crystal structures at AB3 composition are discussed. Prediction of concomita...

This essay provides a perspective on several issues in valence bond theory: the physical significance of semilocal bonding orbitals, the capability of valence bond concepts to explain systems with multireferences character, the use of valence bond theory to provide analytical representations of potential energy surfaces for chemical dynamics by the method of semiempirical valence bond potential...

Peridynamic models that aim to incorporate a given classical local continuum stress-deformation response function typically start with a nonlocal averaged analog to the deformation gradient as input to the given local stress-deformation response function. This approach has been observed to allow unphysical deformations such as interpenetration and cause loss of linear stability. This paper desc...

The dissociation mechanism of duplex DNA has been investigated in detail by collision-induced dissociation experiments at different collision regimes. MS/MS experiments were performed either in a quadrupole collision cell (hybrid quadrupole-TOF instrument) or in a quadrupole ion trap with different activation times and energies. In addition to the noncovalent dissociation of the duplex into the...

We present the results of calculations of surface relaxations, rumplings, energetics, optical band gaps, and charge distribution for the SrZrO(3) and PbZrO(3) (001) and (011) surfaces using the ab initio code CRYSTAL and a hybrid description of exchange and correlation. We consider both SrO(PbO) and ZrO(2) terminations of the (001) surface and Sr(Pb), ZrO, and O terminations of the polar SrZrO(...

We devise a nonlocal correlation energy functional that describes the entire range of dispersion interactions in a seamless fashion using only the electron density as input. The new functional is considerably simpler than its predecessors of a similar type. The functional has a tractable and robust analytic form that lends itself to efficient self-consistent implementation. When paired with an ...

In a recent Letter [1], the authors construct a machine learning (ML) model of molecular atomization energies, which they compare to bond counting (BC) and the PM6 semiempirical method [2]. However, their ML model was trained and tested on density functional theory (DFT) energies while BC and PM6 are fit to standard enthalpies. For fair comparison, bond energies are refit to DFT data and PM6 is...