On the Origin and Structure of the First Sharp Diffraction Peak of Amorphous Silicon

The structure of the first sharp diffraction peak (FSDP) amorphous silicon (${\it a}$-Si) near 2 Angstrom$^{-1}$ is addressed with particular emphasis on position, intensity, and width curve. By studying a number continuous random network (CRN) models ${\it a}$-Si, it shown that position intensity FSDP are primarily determined by radial atomic correlations in length scale 15 Angstroms. A shell-by-shell analysis contribution from different shells reveals key contributions to originate second fourth network, which accompanied background shell small residual corrections distant shells. results numerical calculations complemented phenomenological discussion relationship between peaks factor wavevector space reduced pair-correlation function real space. An approximate functional relation average second-neighbor distance Si atoms derived, corroborated calculations.