# General properties¶

To analyze some or all

*energies*and other properties, such as*total pressure*,*pressure tensor*,*density*,*box-volume*and*box-sizes*, use the program gmx energy. A choice can be made from a list a set of energies, like potential, kinetic or total energy, or individual contributions, like Lennard-Jones or dihedral energies.The *center-of-mass velocity*, defined as

(1)¶\[{\bf v}_{com} = {1 \over M} \sum_{i=1}^N m_i {\bf v}_i\]

with \(M = \sum_{i=1}^N m_i\) the total mass of the system, can be
monitored in time by the program gmx traj `-com -ov`

. It is however
recommended to remove the center-of-mass velocity every step (see
chapter Algorithms)!