title: Free energy calculations for molecular solids using GROMACS.
abstract: In this work, we describe a procedure to evaluate the free energy of molecular solids with the GROMACS molecular dynamics package. The free energy is calculated using the Einstein molecule method that can be regarded as a small modification of the Einstein crystal method. Here, the position and orientation of the molecules is fixed by using an Einstein field that binds with harmonic springs at least three non-collinear atoms (or points of the molecule) to their reference positions. The validity of the Einstein field is tested by performing free-energy calculations of methanol, water (ice), and patchy colloids molecular solids. The free energies calculated with GROMACS show a very good agreement with those obtained using Monte Carlo and with previously published results.
authors.affiliation: Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain. aragones@mit.edu
authors.forename: J L
authors.initials: JL
authors.lastname: Aragones
authors.forename: E G
authors.initials: EG
authors.lastname: Noya
authors.forename: C
authors.initials: C
authors.lastname: Valeriani
authors.forename: C
authors.initials: C
authors.lastname: Vega