Closed-form expressions for correlated density matrices: application to dispersive interactions and example of (He)2
arXiv:physics/0606140 · doi:10.1063/1.2358977
Abstract
Empirically correlated density matrices of N-electron systems are investigated. Exact closed-form expressions are derived for the one- and two-electron reduced density matrices from a general pairwise correlated wave function. Approximate expressions are proposed which reflect dispersive interactions between closed-shell centro-symmetric subsystems. Said expressions clearly illustrate the consequences of second-order correlation effects on the reduced density matrices. Application is made to a simple example: the (He)2 system. Reduced density matrices are explicitly calculated, correct to second order in correlation, and compared with approximations of independent electrons and independent electron pairs. The models proposed allow for variational calculations of interaction energies and equilibrium distance as well as a clear interpretation of dispersive effects on electron distributions. Both exchange and second order correlation effects are shown to play a critical role on the quality of the results.
22 pages
References in corpus (10)
- Van der Waals Energies in Density Functional Theory
- Long-range/short-range separation of the electron-electron interaction in density functional theory
- Van der Waals forces in density functional theory: perturbational long-range electron interaction corrections
- Unified Treatment of Asymptotic van der Waals Forces
- Correlation kinetic energy of many-electron systems: a modified Colle-Salvetti approach
- Interpreting Compton anisotropy of ice Ih: a cluster partitioning method
- Exact Kohn-Sham versus Hartree-Fock in momentum-space: examples of two-fermion systems
- The Van der Waals interaction of the hydrogen molecule - an exact local energy density functional
- A cluster partitioning method: determination of density matrices of solids and comparison with X-ray experiments
- Angular versus radial correlation effects on momentum distributions of light two-electron ions