SPRING_V0
SPRING_V0 = [real (array)]
Description: Consider the bias potential of the form:
[math]\displaystyle{
\tilde{V}(\xi_1,\dots,\xi_{M_8}) = \sum_{\mu=1}^{M}\frac{1}{2}\kappa_{\mu} (\xi_{\mu}(q)-\xi_{0\mu})^2 \;
}[/math]
where the sum runs over all ([math]\displaystyle{ M_8 }[/math]) coordinates the potential acts upon ([math]\displaystyle{ \xi_{\mu}(q) }[/math]), which are defined in the ICONST-file by setting the status to 8.
Optionally, the position of minimum ([math]\displaystyle{ \xi_{0\mu} }[/math]) can be shifted at a constant rate [math]\displaystyle{ \dot{\xi}_{\mu} }[/math] every MD step, i.e.
[math]\displaystyle{
\xi_{0\mu}(t+\Delta t) = \xi_{0\mu}(t) + \dot{\xi}_{\mu}(q)\Delta t \;
}[/math]
where [math]\displaystyle{ \Delta t }[/math] is the time step used in MD (POTIM).
The rate [math]\displaystyle{ \dot{\xi}_{\mu} }[/math] can be defined via the parameter SPRING_V0 and its units are [math]\displaystyle{ uc/fs }[/math], where [math]\displaystyle{ uc }[/math] corresponds to the units of the coordinate the potential acts upon (e.g., [math]\displaystyle{ {\AA} }[/math] for coordinates with flag R, [math]\displaystyle{ rad. }[/math] for coordinates with flag A, dimensionless for coordinates with flag W, etc...).
The number of items defined via SPRING_V0 must be equal to [math]\displaystyle{ M_8 }[/math], otherwise the calculation terminates with an error message.