The structures, electron affinities and bond dissociation energies of BrO(4)F/BrO(4)F(-) species have been investigated with five density functional theory (DFT) methods with DZP++ basis sets. The planar F-Br...O(2)...O(2) complexes possess (3)A' electronic state for neutral molecule and (4)A' state for the corresponding anion. Three types of the neutral-anion energy separations are the adiabat...

We report the parametrization of a density functional tight binding method (DFTB3) for copper in a spin-polarized formulation. The parametrization is consistent with the framework of 3OB for main group elements (ONCHPS) and can be readily used for biological applications that involve copper proteins/peptides. The key to our parametrization is to introduce orbital angular momentum dependence of ...

We report the first computations of circularly polarized luminescence (CPL) rotatory strengths at the equation-of-motion coupled cluster singles and doubles (EOM-CCSD) level of theory. Using a test set of eight chiral ketones, we compare both dipole and rotatory strengths for absorption (electronic circular dichroism) and emission to the results from time-dependent density-functional theory (TD...

A set of design rules for the prediction of relative stabilities of methoxy substituted naphthyl methyl carbocations are presented based on a series of DFT calculations. The peri-effect, over-crowding, substitutions on the ring carrying the CH(2)(+) group and substitution on the opposite ring are the principal factors that influence the stability of the carbocations. All of these factors have t...

The H, C and H, C COSY NMR spectra of salicylohydroxamic acid (sha) were measured in DMSO-d6 solution. The B3LYP GIAO method with the 6-311þþG(d,p) basis set was chosen to reproduce the experimental spectra. All possible zusammen and entgegen conformers of monomeric sha were computed. After geometry optimisation (B3LYP/6311þþG(d,p)) only nine independent models of the molecule were shown to be ...

A combined DFT quantum mechanical and AMBER molecular mechanical potential (QM/MM) is presented for use in molecular modeling and molecular simulations of large biological systems. In our approach we evaluate Lennard-Jones parameters describing the interaction between the quantum mechanical (QM) part of a system, which is described at the B3LYP/6-31+G* level of theory, and the molecular mechani...

A conformational analysis of the methanesulfonamide-N,N'-1,2-ethanediylbis (msen) was performed by using vibrational and NMR spectroscopies as well as theoretical computations. The possible stable conformers of msen on its potential energy surface were investigated by semi-empirical PM5 method and appropriate structures were defined with B3LYP hybrid density functional theory (DFT) method along...

Small peptides are model molecules for the amino acid residues that are the constituents of proteins. In any bottom-up approach to understand the properties of these macromolecules essential in the functioning of every living being, to correctly describe the conformational behaviour of small peptides constitutes an unavoidable first step. In this work, we present an study of several potential e...