| Electrostatic interaction is one of the basic interactions in the physical world. This interaction plays a dominant role in almost every condensed matter system. To evaluate this interaction in a large ensemble is always a vital and challenging task. In this thesis, a method that can explicitly describe the long-range Coulomb interaction for the QM/MM scheme is developed after systematically analyzing the behavior of the long-range Coulomb interaction. This method is further implemented into the simulation packet by a carefully designed algorithm. The correctness of this theory and the performance of our algorithm are verified by: (1) calculations of the crystal structures, (2) QM/MM simple calculations of small ions and molecules, (3) simulations of cations, anions, and small molecules inside aqueous solution, and (4) simulation of the Sodium Chloride crystal structure (Chapter 5). Analysis of this data shows that the long-range Coulomb interaction has a profound effect on the detailed configuration of a molecules or crystal than on its energy. |
