Vreco_CPMD

This program is useful for reconstructing the free energy surface from a metadynamics simulation using CPMD. There is no limitation on the number of collective variables (CV) the program can handle. For runs with 1 (2) CVs, the 2D (3D) reconstructed free energy surfaces, can be viewed in GNUPLOT/OpenDX. For a 3 CV case, it is possible to print the 4D free energy surface in a cube file format (for use with VMD/OpenDX as visualizer).

It is important to note that, $F(s)$ , the free energy in collective variable space, is printed, where

$$F(s) = -\sum_t V(t,s).$$

Here $V(t,s)$ is the biasing potential added at time $t$ in the collective variable space $s$ .

The program reads the files colvar_mtd and parvar_mtd generated by CPMD during a metadynamics run to reconstruct the free energy surface. Both files are in portable text format. The centers and scaling factors of the gaussian hills generated during the runs are taken from colvar_mtd and the width and heights of the gaussians are read from the parvar_mtd file.

For more details please see the documentation enclosed in the distribution available from the contrib directory on http://www.cpmd.org/. The distribution also contains several examples for how to plot and visualize the data.

In addition a tool mtd_restart_extract is available to extract the two files to reconstruct the two text files required for the free energy surface reconstruction from the binary MTD_RESTART file.