First Principles Calculations Of Materials And Thin Films Of Metal Magnesium And Beryllium Body

In this thesis, we use first-principles approach to calculate quantum size effect and the atomic hydrogen adsorption properties in Be and Mg thin films. Also, we have given a detailed study on the thermodynamic properties and phase transition of bulk Be under high pressure, by use of analysis of its electronic structure and phonon spectrum. The thesis has been divided into the following five parts:In Chapter 1, we briefly introduce the development of ab initio calculation method and its application in exploring quantum size effects and lattice dynamics in metals.In Chapter 2, we mainly introduce the density functional theory (DFT) as well as some popular ab initio software packages, which are our theoretical foundation and computational implementation to deal with the issues discussed in this thesis.In Chapter 3, we have carried out first-principles calculations of Be(0001), Mg(0001) thin films to study the oscillatory quantum size effects exhibited in the surface energy, work function, and binding energy of the atomic hydrogen monolayer adsorption. The calculated energetics of Be, Mg films and the properties of atomic H adsorption onto Be(0001) , Mg(0001) surface are featured by a quantum oscillatory behavior.In Chapter 4, we present a first-principles study of the atomic hydrogen adsorption onto the Be(l01|-0)thin film. There are two types of Be (101|-0) surfaces according to the interlayer spacing between the surface and its nearest-neighbor layer. We show that the H adsorption features on these two kinds of surfaces are remarkably different. The work function, averaged electrostatic potential, and the local charge density consistently show that the charge is transferred from H to Be for L-type surfaces, while the transfer process is inverted for S-type surfaces.In Chapter 5, we calculate the electric structure and lattice dynamics of bulk Be with the generalized gradient approximation (GGA). We present various properties of Be such as c/a ratio, the bulk modulus, poisson's ratio and equation of state. We calculate the enthalpy, charge density, band structure and phonon spectrum of two phases (BCC, HCP) under different pressure. The results are in good agreement with experimental results.