Application of a hybrid quantum mechanics and empirical moleculardynamics multiscale method to carbon nanotubes

We present a hybrid multiscale method for coupling quantum mechanicsto empirical molecular dynamics, which is named as hybrid energydensity method. In this approach, quantum mechanical treatment isspatially confined to a small region, surrounded by a largermolecular mechanical region. A unified expression of total energycombining quantum mechanical and molecular mechanical descriptions,is given by employing a localized energy and a weight associatedwith it on each site. And we can perform the dynamical simulationsof entire system according to the given total energy. We use thehybrid energy density method to simulate two models of carbonnanotubes (CNT): one is a long CNT with an open end, and the other along CNT containing a di-vacancy under stretching. Calculations ofthe two CNT models demonstrate that the hybrid multiscale method isrequired to accurately treat the local quantum mechanical regionwith the influence of the larger molecular mechanical region. Copyright Springer 2008