Beyond standard ab initio molecular dynamics
The discussion up to this point has revolved essentially around the “standard” ab initio molecular dynamics methodologies. The notion “standard” means in particular that classical nuclei evolve adiabatically in the electronic ground state in the microcanonical ensemble. In addition, it is assumed that the electronic structure of all constituents of the system is treated on an equal footing. This combination allows already a multitude of applications, but many circumstances exist where the underlying approximations or restrictions break down or are unsatisfactory. Among these cases are situations where:
(i) It is necessary to keep the temperature and/or pressure constant, such as ...