报告题目：Quantum Mechanical Simulations of Complex Systems: O(N) TDDFT and QM/EM Method
报 告 人：ChiYung Yam (任志勇 特聘研究员)
北京计算科学研究中心
时 间：10月15日(周二) 下午16:00
地 点：卢嘉锡楼报告厅（202）
欢迎感兴趣的老师与同学参加，谢谢 ！
能源材料化学协同创新中心
biwn必赢
2013-10-11
Abstract
The poor scaling of many existing quantum mechanical methods with respect to the system size
hinders their applications to large systems. A linear-scaling time-dependent density-functional
theory is developed to study excited states of complex molecular systems. Instead of many-body
wavefunction, the equation of motion is solved for the reduced single-electron density matrix in the
time domain. The time-dependent first-order response of the density matrix due to an external
perturbation is solved using Chebyshev method with high efficiency and accuracy. Linear-scaling
of CPU time and memory usage with the system size is achieved by exploring the sparsity of the
involving matrices as well as by introduction of a cutoff for the first-order density matrix. To
further increase the efficiency, a hybrid quantum mechanics/electromagnetics (QM/EM) method is
developed to model electronic devices at nanoscale. The whole simulation domain is divided into
QM and EM regions and solved in a self-consistent manner between quantum and classical models.
Potential distributions and current densities at the interface are exploited as the boundary conditions
for information exchange between the two regions. The method is expected to bridge the gap
between quantum mechanics simulation and circuit modeling.
