A formula to calculate the charge penetration energy that results when two charge densities overlap has been derived for molecules described by an effective fragment potential (EFP). The method has been compared with the ab initio charge penetration, taken to be the difference between the electrostatic energy from a Morokuma analysis and Stone’s Distributed Multipole Analysis. The average absol...

Ab initio calculations have been carried out to investigate the structure and infrared spectrum of BrH:NH3, and to resolve the discrepancies found between its computed harmonic and experimental spectrum. MP2/6-31+G(d, p) and MP2/aug -cc-pVDZ potential surfaces have been constructed, and a model two-dimensional nuclear vibrational problem has been solved to obtain the fundamental dimer stretchi...

The adsorption of molecular hydrogen on sulfurand chlorine-covered Pd(100) in a (2×2) geometry is studied by ab initio molecular dynamics simulations. The potential energy surfaces of H2/S(2 × 2)/Pd(100) and H2/Cl(2× 2)/Pd(100) are rather similar. Consequently, also the dependence of the sticking probability on incident kinetic energy, angle of incidence and internal excitations are very close....

Excitation of tert-butylnitrite into the first and second UV absorption bands leads to efficient dissociation into the fragment radicals NO and tert-butoxy in their electronic ground states P and E, respectively. Velocity distributions and angular anisotropies for the NO fragment in several hundred rotational and vibrational quantum states were obtained by velocity-map imaging and the recently ...

We have studied the adsorption of O2 on the Cu(100) surface using both static potential energy surface (PES) calculations and ab initio molecular dynamics. The dynamical calculations complement the PES results, revealing steering effects which could not be predicted based on the static calculations only. We study the effect of oxidation and Ag doping on O2 adsorption dynamics. The results are d...

The ant colony algorithm has been applied to the problem of finding the minimal potential energy configuration of a small physical system (cluster) of atoms interacting via the Lennard–Jones phenomenological potential. The ants were positively motivated if their activity (displacement of atomic positions) leads to a lower total potential energy of the system. Starting from a random spatial dist...

A variety of chemical systems exhibit multiple reaction pathways that adjoin to a common reactant state. In fact, any reaction producing side products or proceeding via a stable intermediate involves a species possessing at least two reaction pathways. Despite improvements in ab initio transition-state search algorithms it remains difficult to detect multiple reaction pathways. Typically, multi...

Previously we searched for the ab initio global minima of several SixHy clusters by a genetic algorithm in which we used the AM1 semiempirical method to facilitate a rapid energy calculation for the many different cluster geometries explored. However, we found that the AM1 energy ranking significantly differs from the ab initio energy ranking. To better guarantee locating the ab initio global m...

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...

A polarizable water pair potential was determined by fitting a potential form to microwave, terahertz, and mid-infrared (D2O)2 spectra through a rigorous calculation of the water dimer eigenstates. It accurately reproduces most ground state vibration-rotation-tunneling spectra and yields excellent second viral coefficients. The calculated dimer structure and dipole moment are very close to thos...