An embedded-atom potential has been constructed for the intermetallic compound B2-NiAl by fitting to both experimental properties and ab initio data. The ab initio data have been generated in the form of energy-volume relations for a number of alternative structures of NiAl and Ni3Al, as well as for Ni and Al. The potential accurately reproduces the basic lattice properties of B2-NiAl, planar f...

A considerable efforr has been devoted to ab initio theoretical studies Cl-161 * of the H4 potential surface in order to locate a structure that might correspond to the transition state for the four-center exchange reaction H, + D2 + 2HD and to characterize the long-range intermolecular interaction. To date a satisfactory structure for the transition state has not been located. Various shock-tu...

The recently developed effective fragment potential (EFP) method is used to study the effect of two, four, six, and eight solvating water molecules on the Menshutkin reaction between ammonia and methyl bromide. The EFP method reproduces all ab initio geometries and energetics (including zero-point energy, thermal, and entropy effects) for the two-water case very accurately. Energetics from all ...

The (4, +) energy surface of blocked alanine (N-acetyl-N'-methyl alanineamide) was calculated at the Hartree-Fock (HF)/6-31G* level using ab initio molecular orbital theory. A collection of six electrostatic models was constructed, and the term electrostatic model was used to refer to (1) a set of atomic charge densities, each unable to deform with conformation; and (2) a rule for estimating th...

vinblastine is an important anticancer agent known to diminish microtubule assembly. ab initio calculations are applied to examine the structural properties and different energies of vinblastine-tubulin complex in different dielectric constants and temperatures. the aims of this work are discovery the best optimized structure and thermodynamic properties of vinblastine-tubulin complex and compa...

The sticking and scattering of O(2)Pt(111) has been studied by tight-binding molecular dynamics simulations based on an ab initio potential energy surface. We focus, in particular, on the sticking probability as a function of the angle of incidence and the energy and angular distributions in scattering. Our simulations provide an explanation for the seemingly paradox experimental findings that ...

The vapour produced upon mild heating of hexa-tert-butyldisilane (superdisilane) has been studied by gas electron diffraction and ab initio molecular orbital calculations; the disilane is not observed in the vapour, and the observed radical structure is not the lowest energy structure predicted ab initio.

Ab initio calculations employing the coupled-cluster method, with single and double substitutions and accounting for triple excitations noniteratively [CCSD(T)], are used to obtain accurate potential energy curves for the K(+)He, K(+)Ne, K(+)Ar, K(+)Kr, K(+)Xe, and K(+)Rn cationic complexes. From these potentials, rovibrational energy levels and spectroscopic parameters are calculated. In addit...

We study the thermodynamics of Na8 and Na20 clusters using multiple-histogram methods and an ab initio treatment of the valence electrons within density functional theory. We consider the influence of various electron kinetic-energy functionals and pseudopotentials on the canonical ionic specific heats. The results for all models we consider show qualitative similarities, but also significant t...

The effect of molecular dissociation on the exchange-correlation Kohn-Sham potential vxc has been studied by the construction of vxc from the ab initio correlated density r for the monohydrides XH ~X5Li, B! at several bond distances R~X—H!. The molecular dissociation manifests itself in the formation of a characteristic peak of vxc in the bonding region. The partially integrated conditional pro...