From the Cluster to the Liquid Ab Initio Calculations on Realistic Systems Based on First Principles Molecular Dynamics英文电子书.pdfVIP

7 From the Cluster to the Liquid: Ab-Initio Calculations on Realistic Systems Based on First-Principles Molecular Dynamics 1 2 1,2 3 C. Massobrio , M. Celino , Y. Pouillon , and I.M.L. Billas 1 Institut de Physique et de Chimie des Mat´eriaux de Strasbourg, 23 rue du Loess, BP 43, 67034 Strasbourg Cedex 2, France 2 Ente per le Nuove Tecnologie, l’Energia e l’Ambiente, C.R. Casaccia, CP 2400, 00100 Roma, Italy and Istituto Nazionale per la Fisica della Materia, Unit`a di Ricerca Roma1, Italy 3 D´epartement de Biologie et de G´enomique Structurales, Institut de G´enetique et de Biologie Mol´eculaire et Cellulaire, 1 rue Laurent Fries, BP 10142, 67404 Illkirch, France Abstract. In both clusters and disordered systems the determination of struc- tural properties often relies on qualitative interpretations of experimental data. First-principles molecular dynamics provides a reliable atomic-scale tool to opti- mize geometries and follow the dynamical evolution at different temperatures. We present three examples of application of first-principles molecular dynamics to the study of finite systems and disordered, bulk networks. In the first case, devoted to the copper oxide clusters CuO2 and CuO6 , the account of temperature effects and a careful search of all isomer allows to complement effectively photoelectron spec- troscopy data. In the second example, we analyze the behavior of the C60 fullerene when one or two silicon atoms are inserted in the cage to replace carbon atoms. Silicon atoms correspond to chemically reactive sites of the fullerenes, giving rise to local structural distortions. Then, we describe the determination of the structure for liquid SiSe2 at thermal equilibrium. The microscopic origins of intermediate range order are rationalized in terms o