Borg Mikael, Stampfl Catherine, Mikkelsen Anders, Gustafson Johan, Lundgren Edvin, Scheffler Matthias, Andersen Jesper N
Department of Synchrotron Radiation Research, Institute of Physics, Lund University, Sweden.
Chemphyschem. 2005 Sep 5;6(9):1923-8. doi: 10.1002/cphc.200400612.
The structural phases of Al(x)Na(1-x) surface alloys have been investigated theoretically and experimentally. We describe the system using a lattice-gas Hamiltonian, determined from density functional theory, together with Monte Carlo (MC) calculations. The obtained phase diagram reproduces the experiment on a quantitative level. From calculation of the (configurational) density of states by the recently introduced Wang-Landau MC algorithm, we derive thermodynamic quantities, such as the free energy and entropy, which are not directly accessible from conventional MC simulations. We accurately reproduce the stoichiometry, as well as the temperature at which an order-disorder phase transition occurs, and demonstrate the crucial role, and magnitude, of the configurational entropy.
已对Al(x)Na(1-x)表面合金的结构相进行了理论和实验研究。我们使用从密度泛函理论确定的晶格气体哈密顿量以及蒙特卡罗（MC）计算来描述该系统。所得相图在定量水平上再现了实验结果。通过最近引入的王-兰道MC算法计算（构型）态密度，我们推导出了传统MC模拟无法直接获得的热力学量，如自由能和熵。我们准确再现了化学计量比以及发生有序-无序相变的温度，并证明了构型熵的关键作用和大小。
