Showing papers by "Rajendra R. Zope published in 2000"

Temperature dependence of the polarizability of sodium clusters

Abstract: We calculate the static dipole polarizability at finite temperature of sodium clusters of size 8, 20, 40, 55, 93, and 139 using an extended Thomas-Fermi description of the valence electrons. We find polarizabilities at 300 K that are roughly $15%$ greater than at 0 K, consistent with discrepancies between theoretical polarizabilities at 0 K and measured polarizabilities. We predict that a sharp rise in the polarizability, of about $5%$, occurs for sizes of 55 and 139 when the cluster melts, offering the possibility of an alternative method for measuring cluster melting points.

Momentum-space properties of atoms: Application of the generalized-gradient approximation

Abstract: The calculations of Compton profiles and various $〈{p}^{n}〉$-expectation values are carried out for a few closed-shell atomic systems within Perdew-Burke-Ernzerhof (PBE), Perdew-Wang 1991 (PW91) and Becke-Lee-Yang-Parr (BLYP) generalized-gradient approximations. The calculated Compton profiles and the moments are compared with their local-density approximation (LDA) and more accurate available theoretical or experimental counterparts in order to investigate the supremacy of generalized gradient approximation (GGA) over LDA in predicting the momentum-space properties. The results show that GGA improves the Compton profiles marginally. The PBE and PW91 values of Compton profiles are practically identical and are slightly better than BLYP. Further comparison of GGA and LDA results with those calculated within self-interaction corrected LDA (SICLDA) formalism demonstrates the importance of proper description of the valence region in the study of Compton profiles. GGA values of the moments of electron momentum density are found to be, in general, more accurate than their LDA counterparts.