文档介绍：高压下锇的第一性原理计算研究
梁拥成
导师:方忠,郭万林
2006-9-14
南京航空航天大学纳米科学研究所
中国科学院物理研究所理论组
主要内容:
研究背景
计算细节
结果与讨论
结论
研究背景
Osmium has the Lowest Experimentally pressibility
Hyunchae Cynn, John E. Klepeis, Choong-Shik Yoo, and David A. Young
(2002)
Os: 晶体结构是hcp
原子序数76

B0=462GPa
Phys. Rev. B 70_012101(2004)
B0=395GPa
(2004)
B0=411GPa
or the electronic topological transition (ETT)?.
2. the passage of the maxima in band h7 below the Fermi energy pression resulting in the collapse of the small hole ellipsoid?
The main purpose of the present work:
Bulk modulus: larger or smaller that of diamond? The effect of SOC on it?
2. ETT evidence from the calculational perspective ?
first-principles PW-PP in BSTATE (Beijing Simulation Tool for Atom Technology)
(2)Norm-conserving pseudopotential, 5d66s2 atomic configurations, GGA
(3)We consider unit-cell volumes ranging from 150 to 197 Bohr3 and calculate dense volume points on small interval of Bohr3 attempting to find whether to have the kink of c/a ratio versus pressure .
(4)calculate the total energy of a hexagonal system included and excluded spin-orbit coupling (SOC)
(5)wave functions cutoff Ryd and charge density cutoff 400 Ryd
(6)For the Brillouin zone sampling : 18x18x14 Monkhorst-Pack mesh
计算细节
结果与讨论
(1)状态方程
The third-order Birch –Mumaghan EOS:
(2)轴间比c/a和晶格常数
Phys. Rev. B 72 174103