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PENALTYPOT

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 ICONST. In analogy to the time-dependent bias potential generated in metadynamics, the bias potential is defined as a superposition of Gaussian hills, see eq. 6.18. Each line in PENALTYPOT represents one (multidimensional) Gaussian:

$ x_1$ $ x_2$ ... $ x_m$ $ h$ $ w$

where $ x_1$ to $ x_m$ stand for the position in the space of active coordinates, and $ h$ and $ w$ are the height and width of the Gaussian, respectively (note that both positive and neative values are allowed for the parameter $ h$). For example, if two active coordinates with STATUS=5 are defined in ICONST:

R 1 5 5
R 1 6 5

then each line in the PENALTYPOT must contain four items. The bias potential 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

creates a "wall" that should prevent the bond length between the atoms $ 1 $ and $ 5$ to exceed the value of 1.6 Å.



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