SPRING_V0

SPRING_V0 = [real (array)]

Description: Consider the bias potential of the form:

${\displaystyle \tilde{V}(\xi_1,\dots,\xi_{M_8}) = \sum_{\mu=1}^{M}\frac{1}{2}\kappa_{\mu} (\xi_{\mu}(q)-\xi_{0\mu})^2 \; }$

where the sum runs over all ( $M_8$ ) coordinates the potential acts upon ( $\xi_{\mu}(q)$ ), which are defined in the ICONST-file by setting the status to 8. Optionally, the position of minimum ( $\xi_{0\mu}$ ) can be shifted at a constant rate $\dot{\xi}_{\mu}$ every MD step, i.e.

${\displaystyle \xi_{0\mu}(t+\Delta t) = \xi_{0\mu}(t) + \dot{\xi}_{\mu}(q)\Delta t \; }$

where $\Delta t$ is the time step used in MD (POTIM). The rate $\dot{\xi}_{\mu}$ can be defined via the parameter SPRING_V0 and its units are $uc/fs$ , where $uc$ corresponds to the units of the coordinate the potential acts upon (e.g., ${\AA}$ for coordinates with flag R, $rad.$ for coordinates with flag A, dimensionless for coordinates with flag W, etc...). The number of items defined via SPRING_V0 must be equal to $M_8$ , otherwise the calculation terminates with an error message.

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