The influence of a simple semiempirical van der Waals vdW correction on the description of dispersive, covalent, and ionic bonds within density functional theory is studied. The correction is based on the asymptotic London form of dispersive forces and a damping function for each pair of atoms. It thus depends solely on the properties of the two atoms irrespective of their environment and is nu...

Interaction enthalpies for six base pairs have been computed at a variety of efficient levels of electronic structure theory and compared to experiment. In addition to previously defined levels of theory, modified Hamiltonians with adjusted parameters in hybrid Hartree-Fock/density functionals and semiempirical neglect-of-diatomic-differential-overlap models were examined. Of the pure and hybri...

Predicting the masses of baryons containing one or two heavy quarks The Feynman-Hellmann theorem and semiempirical mass formulas are used to predict the masses of baryons containing one or two heavy quarks. In particular, the mass of the Λ b is predicted to be 5620 ± 40 MeV, a value consistent with measurements. In a recent paper [1], the Feynman-Hellmann theorem [2,3] and semiempirical mass fo...

Inelastic x-ray scattering data of liquid Li, Na, and Al for dynamical structure factors have been analyzed by proposing a semiempirical model. The model is based on the extension of the hydrodynamic model to the viscoelastic region so that it satisfies the first four nonvanishing sum rules. It has been found that the semiempirical model fits well with the x-ray scattering data for liquid metal...

A force field for vanadium-oxos was developed and tested with a variety of complexes with coordination numbers of 5 or 6 and formal oxidations states of +4 or +5 on the metal. Similarly, a semiempirical quantum mechanical method for transition metals was extended to vanadium. In this research soft and hard ligands were studied, as were ligands coordinated through single, multiple, and dative bo...

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...