Correlation calculations for the reconstruction of the Si (100) surface

TL;DR

This study uses advanced ab initio calculations to analyze the Si(100) surface, revealing a symmetric dimer structure and providing detailed insights into the electronic states and surface reconstruction energetics.

Contribution

It presents the first multi-reference configuration interaction calculations for the Si(100) surface, showing a symmetric dimer ground state contrary to some previous results.

Findings

Symmetric dimer structure is energetically favored.

Energy gain of 1.75 eV from dimer formation.

Bond length of 2.35 Å matches bulk silicon.

Abstract

Ab initio multi-reference configuration interaction calculations are performed for the Si(100) surface using a cluster approach. The convergence with respect to the cluster size is checked and the final results are taken from a $Si_{32} H_{28}$ cluster which models two dimers and six bulk layers. We find for the ideal as well as for the p($1\times 2$) reconstruction a singlet ground state consisting of several configurations. The energy gain due to forming the symmetric dimer in the p($1\times 2$) structure is 1.75 eV, the bond length of the dimer is 2.35 \AA which is very close to the bulk value. In contradiction to the LDA results and in agreement with previous correlation calculations we do not find an asymmetric p($1\times 2$) structure.