Effective Repulsion Energy Research Articles

Effective on-site Repulsion in Molecular Conductors with Dimeric Structure: Is the Transfer Integral a Good Measure of Correlation?

The effective repulsive energy between the carriers in a molecular dimer has been examined in terms of the extended Hubbard model. The intermolecular Coulomb repulsion, V, rather than the intradimer transfer integral, t, has been shown to give major contribution to the effective repulsion in a strongly dimerized case. The effective repulsion of the dimer, as well as t, increases upon dimerization, for this reason. This analysis has been applied also to a two-level system, so that the strength of correlation is related to the structural features.

QUANTUM CELL MODEL FOR He II AT NONZERO TEMPERATURE

A previous quantum cell-model development is expanded to treat the solid-superfluid phase transition and the zero-momentum occupation at temperatures other than absolute zero. Application is made to liquid He II, which is studied at various pressures out to temperatures of about a degree absolute. The effective repulsive energy, along the solid–superfluid transition, is determined for pairs of 4He atoms localized in cells of volume equal to the specific volume.