Structure and effective pair potential of liquid silicon

Liquid silicon has a particular structural feature characterized by a small hump on the higher were vector side of the first peak in the structure factor. The effective pair potential of liquid silicon has been estimated from the experimental structure factor data using the modified hypernetted chain (MHNC) equation. The resultant pair potential shows the ledge-type feature in the repulsive core part, close to the first peak of the pair distribution function, as well as the long-range oscillatory behavior. This pair potential was also compared with the theoretical one calculated using the pseudopotential theory of metals and good agreement was found although there are differences in detail. The basic structural features including a small hump of the structure factor for liquid silicon can be reproduced by this calculated pair potential. In order to consider a possible origin of the characteristic small hump detected in the structure factor of liquid silicon, the calculations were also made using artificially modified pair potentials. The results suggest that the long-range oscillatory part of the pair potential plays a significant role in producing this particular structural feature of liquid silicon.