Abstract: Over the last several decades, molecular simulation has become a very useful tool in theoretical studies of complex chemical and biological systems. Interplay between analytic theory, simulations, and experiments are changing the way how chemical research is done. The 2013 Nobel prize was awarded to Karplus, Warshel and Levitt, "for the development of multiscale models for complex chemical systems." In this short paper, we discuss briefly the history and basics of theoretical chemistry, especially molecular simulations. The future development in these areas depends heavily on how students of chemistry majors are trained.

Key words: molecular simulation, multi-scale, theoretical chemistry