The aim of the study was to explore the limits of ab initio methods towards the description of excited vibrational levels up to the dissociation limit for molecules having more than two electrons. To this end a high level ab initio potential energy function was constructed for the four-electron LiH molecule in order to accurately predict a complete set of bound vibrational levels corresponding ...

ab initio calculations at hf/6-31g* level of theory for geometry optimization and mp2/6-31g*//hf/6-31g*for total energy calculation are reported for z-cyclooctene (1). the most favorable conformation of 1 is theunsymmetric boat-chair (1-bc) geometry. potential energy profiles for two different boat-chair/boat-chairinterconversion processes were calculated. the process via a chair transition sta...

A moving interpolation technique which provides an accurate representation of potential energy surfaces for polyatomic molecules is presented. The method uses the ab initio energy, energy gradient, and second derivatives calculated at dynamically important configurations. The interpolant of the energy and its derivatives converges to the exact value with increasing number of data. A procedure i...

We survey approaches to nonrelativistic density functional theory (DFT) for nuclei using progress toward ab initio DFT for Coulomb systems as a guide. Ab initio DFT starts with a microscopic Hamiltonian and is naturally formulated using orbital-based functionals, which generalize the conventional local-density-plus-gradients form. The orbitals satisfy single-particle equations with multiplicati...

We explore and discuss several important issues concerning the derivation of many-body force fields from ab initio quantum chemical data. In particular, we seek a general methodology for constructing ab initio force fields that are ‘‘chemically accurate’’ and are computationally efficient for large-scale molecular dynamics simulations. We investigate two approaches for modeling many-body intera...

Total and partial charge transfer cross sections are calculated in collisions of protons with the nitrogen molecule at energies between 0.1 and 10 keV. Ab initio potential energy curves and nonadiabatic couplings have been obtained for a number of N2 bond lengths using a multireference configuration interaction method. The influence of the anisotropy of the target molecule is investigated. Resu...

In this paper, the numerical solution methods of one- particale, one – dimensional time- independentSchrodinger equation are presented that allows one to obtain accurate bound state eigen values andeigen functions for an arbitrary potential energy function V(x). These methods included the FEM(Finite Element Method), Cooly, Numerov and others. Here we considered the Numerov method inmore details...

Potential energy surfaces of N,N-hydrogen migration of pyrazole and 5-methyl pyrazole for the ground and triplet states were calculated by the ab initio molecular orbital methods. All potential energy surfaces for the N.N-hydrogen shift have high energy barriers. The occurrence of the structural change indispensable to the switching function is doubtful for pyrazole and 5-methyl pyrazole. The s...

0022-2852/$ see front matter 2013 Elsevier Inc. A http://dx.doi.org/10.1016/j.jms.2013.04.002 ⇑ Corresponding author. E-mail address: [email protected] (C. Sousa-S An accurate and comprehensive room temperature rotation-vibration transition line list for phosphine (PH3) is computed using a newly refined potential energy surface and a previously constructed ab initio electric dipole moment...

High-level ab initio electronic structure calculations, including extrapolations to the complete basis set limit as well as relativistic and diagonal Born-Oppenheimer corrections, resulted in a torsional potential of acetaldehyde in its electronic ground state. This benchmark-quality potential fully reflects the symmetry and internal rotation dynamics of this molecule in the energy range probed...