Physics

The quantum nature of matter not only results in exotic proper-ties of strongly correlated condensed matter systems, but is also responsible for remarkable properties of ubiquitous systems like water. In this thesis, we study the role of quantum effects in di-verse condensed matter systems. In the first part of the thesis, we develop a computationally inexpensive alternative method to the path integral (PI) formalism that is capable of including vibrational zero-point quantum effects in classical molecular dynamics (MD) simulations. Our idea is based on the concept of thermostats, used for temperature control in MD. We combine Nose-Hoover (NH) and Generalized Langevin thermostats (GLE) to equilibrate differ-ent dynamical modes to their zero point temperature. We applied our thermostat (NGLE) to a flexible liquid water force field, and structural properties are in good agreement with PIMD with frac-ii