Pressure Calculation in Molecular Dynamics Simulations of Molecular Crystals

Abstract

In molecular dynamics simulations the pressure is usually calculated with molecules as basic units. This approach fails for a polymer, and it is shown that pressure calculation on the basis of individual atoms is equally well possible, even though the forces on the atoms are not pair-additive. The only disadvantage is the need for a larger pressure time constant in simulations where the volume is adjusted to an external pressure. The formalism is tested on the α-D-glucose monohydrate crystal. Some comments are made on the calculation of the temperature in the leap-frog scheme.

Key Words:

• Molecular dynamics simulation
• pressure equation
• α-D-glucose