SCALE_MASS

NAME
SCALE_MASS - Provide the length of the rejection phase

SYNOPSIS
SCALE_MASS   i1 [ i2 ] mass

DESCRIPTION
This command allows to change the mass of selected atoms. i1 is the atom index (according to the ordering in specified in the topology files and JOIN directives in the namelist &PARAMETERS). mass is the new assigned value of the mass to atom i1. If the integer i2 is also specified, atoms with indexes from i1 to i2 are assigned the mass mass.

EXAMPLES
SCALE_MASS 1 2 1.0E40
Masses of atom with index 1 and 2 are set to 1.0E40 uma, to fix them during the simulation. This command can be useful in fast switching alchemical calculations of ligand-protein systems to avoid imposing a harmonic restraint to keep the ligand in the binding site. It can be shown that mass instantaneous isokinetic scaling and restoring in a nonequilibrium processes yields a null contribution to the total work.[]

WARNINGS
This command is inactive during a minimization run (see command MDRUN in &SIMULATION).