Molecular dynamics simulations in a NpT ensemble using non-periodic boundary conditions

In the present work, the general liquid optimized boundary (GLOB) model, which is a discrete/continuum approach for molecular simulations of liquids and solutions, has been extended to include a pressure coupling algorithm based on an extended phase-space scheme. To this end, a definition of the instantaneous pressure for a microscopic system has been derived from the minimum energy principle for the Helmholtz free energy. Applications to a pure liquid, such as water, and an aqueous solution of myoglobin are presented and the results are compared to those obtained using standard periodic boundary conditions (PBC).