σ -bond expression for an analytic bond-order potential: Including π and on-site terms in the fourth moment
Abstract
An improved expression for σ bonds in sp -valent systems is derived for the analytical bond-order potential to four levels. The enhancement concerns the evaluation of the fourth moment of the local density of states with on-site and π terms. The latter introduce a torsional stiffness to the σ -bond order, previously known only for the π -bond order. The relative strength of the π enhancement as compared to the pure σ terms depends on the ratio of the π - and σ -bond integrals of the specific system. In the cubic diamond phase it is large for silicon (48%) and rather small for carbon (5%) . The potential parameters are given for silicon and the predicted properties are compared with ab initio calculations and experimental data.
- Publication:
-
Physical Review B
- Pub Date:
- July 2007
- DOI:
- 10.1103/PhysRevB.76.014306
- Bibcode:
- 2007PhRvB..76a4306K
- Keywords:
-
- 71.15.Mb;
- 34.20.Cf;
- Density functional theory local density approximation gradient and other corrections;
- Interatomic potentials and forces