Cawkwell M J, Coe J D, Yadav S K, Liu X-Y, Niklasson A M N
Theoretical Division, ‡Materials Science and Technology Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.
J Chem Theory Comput. 2015 Jun 9;11(6):2697-704. doi: 10.1021/acs.jctc.5b00143.
The extended Lagrangian Born-Oppenheimer molecular dynamics formalism [Niklasson, Phys. Rev. Lett., 2008, 100, 123004] has been applied to a tight-binding model under the constraint of local charge neutrality to yield microcanonical trajectories with both precise, long-term energy conservation and a reduced number of self-consistent field optimizations at each time step. The extended Lagrangian molecular dynamics formalism restores time reversal symmetry in the propagation of the electronic degrees of freedom, and it enables the efficient and accurate self-consistent optimization of the chemical potential and atomwise potential energy shifts in the on-site elements of the tight-binding Hamiltonian that are required when enforcing local charge neutrality. These capabilities are illustrated with microcanonical molecular dynamics simulations of a small metallic cluster using an sd-valent tight-binding model for titanium. The effects of weak dissipation on the propagation of the auxiliary degrees of freedom for the chemical potential and on-site Hamiltonian matrix elements that is used to counteract the accumulation of numerical noise during trajectories was also investigated.
扩展拉格朗日玻恩-奥本海默分子动力学形式体系[尼克拉斯松，《物理评论快报》，2008年，第100卷，123004]已应用于局部电荷中性约束下的紧束缚模型，以生成具有精确长期能量守恒且在每个时间步减少自洽场优化次数的微正则轨迹。扩展拉格朗日分子动力学形式体系在电子自由度的传播中恢复了时间反演对称性，并且它能够对紧束缚哈密顿量在位元素中的化学势和原子级势能偏移进行高效且精确的自洽优化，这在强制局部电荷中性时是必需的。使用钛的sd价紧束缚模型对一个小金属团簇进行微正则分子动力学模拟，展示了这些能力。还研究了弱耗散对用于抵消轨迹中数值噪声积累的化学势辅助自由度传播以及在位哈密顿矩阵元的影响。
