APPLICATION OF GENERALIZED FILTER-DIAGONALIZATION TO EXTRACT INSTANTANEOUS NORMAL-MODES

In this paper, we apply the generalized filter-diagonalization (GFD) t echnique for extracting normal modes through correlation functions gen erated by molecular dynamics simulation. We test our method on a 256 a rgon particles system. Normal modes are calculated by the power spectr um of the velocity auto-correlation function, generalized filter-diago nalization, and direct diagonalization of the force matrix. The argon cluster provides a rigorous model for the generalized filter-diagonali zation technique since the average separation between adjacent modes i s less than 0.1 cm(-1). Excellent agreement was achieved even for norm al modes that are separated by as little as similar to 0.01 cm(-1).