Kohn–Sham density functional theory is one of the most widely used electronic structure theories. In the pseudopotential framework, uniform discretization of the Kohn–Sham Hamiltonian generally results in a large number of basis functions per atom in order to resolve the rapid oscillations of the Kohn–Sham orbitals around the nuclei. Previous attempts to reduce the number of basis functions per...

We describe a multireference configuration interaction method that takes advantage of local correlation methods in both the internal ~originally occupied! and external ~originally unoccupied or virtual! orbital spaces. In the internal space, implementation of local correlation is trivial and involves neglecting configurations having simultaneous excitations out of widely separated orbitals. In ...

Organic high-spin molecules are ideal model compounds for organic magnetic materials such as organic superparaand ferro-magnets which have recently been attracting increasing interest [1]. The related experimental [2] and theoretical works [3] have been done to serve their molecular design for the last two decades. High-spin polycarbenes as organic high-spin systems, in spite of their highly ch...

An analysis of reaction efficiency is presented for reactions of carbonaceous ions and molecules. Our results show that the combination of experimental rate-coefficient measurements and computations of the condensed Fukui functions of frontier molecular orbitals and pyramidal angles of pi orbitals is very useful for elucidating the reactive sites on fullerene carbon clusters in the gas phase.

The first rare earth metal terminal imido complex has been isolated and structurally characterized. The complex has an extremely short M-N bond length and a nearly linear M-N-C angle. DFT studies showed two p orbitals of N(imido) atom form two bonds with two d orbitals of rare earth metal ion.

Kohn-Sham density functional theory is one of the most widely used electronic structure theories. Uniform discretization of the Kohn-Sham Hamiltonian generally results in a large number of basis functions per atom in order to resolve the rapid oscillations of the Kohn-Sham orbitals around the nuclei. Previous attempts to reduce the number of basis functions per atom include the usage of atomic ...

We have evaluated the NMR shielding tensors for A:T,G:C,A:U in Watson-crick, and U-quartet. We have computed NMR shielding tensors at B31YP level by using 6-31G(d) basis set. We have compute anisotropy and asymmetry in A:T,G:C,A:U and U-quartet. The NMR shielding tensors were calculated using the GIAO method. The natural bonding orbital analysis (NBO) were performed. NBO calculation have been ...

The Pipek-Mezey scheme for generating chemically intuitive, localized molecular orbitals is generalized to incorporate various ways of estimating the atomic charges, instead of the ill-defined Mulliken charges used in the original formulation, or Löwdin charges, which have also been used. Calculations based on Bader, Becke, Voronoi, Hirshfeld, and Stockholder partial charges, as well as intrins...

Here the ab-initio R-Matrix method has been used to carry out electron-molecule collision calculations on the the molecules of interstellar interest C3N, C2H & CN, and molecules found in industrial plasma applications SiBr, SiBr2 and NaI. These were carried out using the UK Molecular R-Matrix codes, along with the Quantemol expert system for running these codes. Calculations have also been carr...