Electron correlations for ground state properties of group IV semiconductors

TL;DR

This paper uses an ab-initio approach to evaluate electron correlations in group IV semiconductors, improving the accuracy of predicted ground state properties like cohesive energies, lattice constants, and bulk modulus.

Contribution

It introduces a method combining cluster calculations and CEPA to accurately account for electron correlations in crystalline semiconductors.

Findings

Recovered about 95% of experimental cohesive energies

Correlation effects reduced lattice constant deviations to within error bounds

Correlation effects brought bulk modulus estimates to about 97% of experimental values

Abstract

Valence energies for crystalline C, Si, Ge, and Sn with diamond structure have been determined using an ab-initio approach based on information from cluster calculations. Correlation contributions, in particular, have been evaluated in the coupled electron pair approximation (CEPA), by means of increments obtained for localized bond orbitals and for pairs and triples of such bonds. Combining these results with corresponding Hartree-Fock (HF) data, we recover about 95 % of the experimental cohesive energies. Lattice constants are overestimated at the HF level by about 1.5 %; correlation effects reduce these deviations to values which are within the error bounds of this method. A similar behavior is found for the bulk modulus: the HF values which are significantly too high are reduced by correlation effects to about 97 % of the experimental values.