An Effective-Medium Tight-Binding Model for Silicon

TL;DR

This paper introduces a novel ab initio effective-medium tight-binding model for silicon that accurately calculates total energies, phonons, and surface properties without empirical fitting, improving computational efficiency and predictive power.

Contribution

The paper presents a new effective-medium tight-binding approach based on first principles, enabling efficient and accurate energy calculations for silicon systems without empirical parameters.

Findings

Accurately predicts phonon energies and elastic constants.

Successfully models surface reconstructions and different structures.

Comparable or better accuracy than empirical tight-binding methods.

Abstract

A new method for calculating the total energy of Si systems is presented. The method is based on the effective-medium theory concept of a reference system. Instead of calculating the energy of an atom in the system of interest a reference system is introduced where the local surroundings are similar. The energy of the reference system can be calculated selfconsistently once and for all while the energy difference to the reference system can be obtained approximately. We propose to calculate it using the tight-binding LMTO scheme with the Atomic-Sphere Approximation(ASA) for the potential, and by using the ASA with charge-conserving spheres we are able to treat open system without introducing empty spheres. All steps in the calculational method is {\em ab initio} in the sense that all quantities entering are calculated from first principles without any fitting to experiment. A complete and detailed description of the method is given together with test calculations of the energies of phonons, elastic constants, different structures, surfaces and surface reconstructions. We compare the results to calculations using an empirical tight-binding scheme.