FIX_FREE_ENERGY

 NAME
FIX_FREE_ENERGY – Set up input for performing a SGE simulation with fixed weight factors.

 SYNOPSIS
FIX_FREE_ENERGY OPEN PATH/filename

 DESCRIPTION
The presence of this command in the input establishes that user-defined weight factors (the $\Delta g_{n \rightarrow m} = g_m - g_n$ difference factors in Eq. 6.8) instead of self-updating free energy differences (the $\Delta f_{n \rightarrow m} = f_m - f_n$ free energy difference in Eq. 6.22) must be used in the SGE simulation. Such factors are kept constant during the simulation run. They are defined in the file named filename. The absolute path (PATH) must be specified to localize filename. If one needs to use the relative path in a many-replica SGE simulation (parallel run) then the working directories of the replicas must be considered the PARXXXX ones. The weight factors $\Delta g_{n \rightarrow m} = g_m - g_n$ are dimensionless and, in filename, must be reported one per line, from $g_{2 \rightarrow 1}$ to $g_{nstates \rightarrow nstates-1}$.

 EXAMPLES
FIX_FREE_ENERGY OPEN ../weight_factors.dat
A SGE simulation is performed with fixed weight factors read from file ../weight_factors.dat.

 DEFAULTS
The absence of the FIX_FREE_ENERGY command in the input implies the use of the BAR-SGE method (see Section 6.3.2) to update the weight factors during the simulation.