PENALTYPOT

File that defines the bias potential for a biased molecular-dynamics run.

At the beginning of each metadynamics simulation, VASP attempts to read the file PENALTYPOT containing the bias potential acting on the geometric parameters with STATUS=5 defined in the ICONST file. In analogy to the time-dependent bias potential generated in metadynamics, the bias potential is defined as a superposition of Gaussian hills. Each line in the PENALTYPOT file represents one (multidimensional) Gaussian:

[math]\displaystyle{ x_1 x_2 ... x_m h w }[/math],

where [math]\displaystyle{ x_1 }[/math] to [math]\displaystyle{ x_m }[/math] stand for the position in the space of active coordinates, and [math]\displaystyle{ h }[/math] and [math]\displaystyle{ w }[/math] are the height and width of the Gaussian, respectively. Note that both positive and negative values are allowed for the parameter [math]\displaystyle{ h }[/math].

For example, if two active coordinates with STATUS=5 are defined in the ICONST file:

R 1 5 5
R 1 6 5 

then each line in the PENALTYPOT must contain four items. The bias potential is defined in the following lines:

1.6 0.8 1.0 0.2
1.6 1.0 1.0 0.2
1.6 1.2 1.0 0.2
1.6 1.4 1.0 0.2
1.6 1.6 1.0 0.2
1.6 1.8 1.0 0.2
1.6 2.0 1.0 0.2

Related tags and articles

MDALGO, ICONST

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