摘要：

In this talk Ⅰ will discuss three developments required for simulating nano-scale devices, namely, (1) linear-scaling calculation for excited states, (2) beyond the Born-Oppenheimer approximation, and (3) quantum chemistry simulation of open systems. Linear-scaling localized-density-matrix (LDM) method has been developed for calculating accurately the excited state properties, for instance, absorption spectrum. It has been implemented with the PPP, CNDO/S, INDO/S, AM1 and PM3 semiempirical Hamiltonians, and applied to nano-sized PPV aggregates and carbon nanotubes. Nuclear dynamics has been simulated simultaneously with the electronic dynamics in the time domain, which is within the framework of the LDM method. Exchange of energy and electrons with the surrounding has been included as well, and interesting results on excited state relaxation and corresponding optical responses will be presented.

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