SPRING V0: Difference between revisions
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Description: Consider the bias potential of the form: | Description: Consider the bias potential of the form: | ||
<math> | <math> | ||
\tilde{V}(\xi_1,\dots,\xi_{M_8}) = \sum_{\mu=1}^{M}\frac{1}{2}\kappa_{\mu} (\xi_{\mu}(q)-\xi_{0\mu})^2 \; | \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> | </math> | ||
where the sum runs over all (<math>M_8</math>) coordinates the potential acts upon (<math>\xi_{\mu}(q)</math>), which are defined in the {{FILE|ICONST}}-file by setting the status to 8. | where the sum runs over all (<math>M_8</math>) coordinates the potential acts upon (<math>\xi_{\mu}(q)</math>), which are defined in the {{FILE|ICONST}}-file by setting the status to 8. | ||
Optionally, the position of minimum (<math>\xi_{0\mu}</math>) can be shifted at a constant rate <math>\dot{\xi}_{\mu}</math> every MD step, i.e. | Optionally, the position of minimum (<math>\xi_{0\mu}</math>) can be shifted at a constant rate <math>\dot{\xi}_{\mu}</math> every MD step, i.e. | ||
<math> | <math> | ||
\xi_{0\mu}(t+\Delta t) = \xi_{0\mu}(t) + \dot{\xi}_{\mu}(q)\Delta t \; | \xi_{0\mu}(t+\Delta t) = \xi_{0\mu}(t) + \dot{\xi}_{\mu}(q)\Delta t \; | ||
</math> | </math> | ||
where <math>\Delta t</math> is the time step used in MD ({{TAG|POTIM}}). | where <math>\Delta t</math> is the time step used in MD ({{TAG|POTIM}}). | ||
The rate <math>\dot{\xi}_{\mu}</math> can be defined via the parameter {{TAG|SPRING_V0}} and its units are <math>uc/fs</math>, where <math>uc</math> corresponds to the units of the coordinate the potential acts upon (e.g., <math>{\AA}</math> for coordinates with <code>flag</code> R, <math>rad.</math> for coordinates with <code>flag</code> A, dimensionless for coordinates with <code>flag</code> W, etc...). | The rate <math>\dot{\xi}_{\mu}</math> can be defined via the parameter {{TAG|SPRING_V0}} and its units are <math>uc/fs</math>, where <math>uc</math> corresponds to the units of the coordinate the potential acts upon (e.g., <math>{\AA}</math> for coordinates with <code>flag</code> R, <math>rad.</math> for coordinates with <code>flag</code> A, dimensionless for coordinates with <code>flag</code> W, etc...). | ||
Revision as of 08:42, 11 April 2023
SPRING_V0 = [real (array)]
Description: Consider the bias potential of the form:
where the sum runs over all () coordinates the potential acts upon (), which are defined in the ICONST-file by setting the status to 8. Optionally, the position of minimum () can be shifted at a constant rate every MD step, i.e.
where is the time step used in MD (POTIM).
The rate can be defined via the parameter SPRING_V0 and its units are , where corresponds to the units of the coordinate the potential acts upon (e.g., for coordinates with flag R, for coordinates with flag A, dimensionless for coordinates with flag W, etc...).
The number of items defined via SPRING_V0 must be equal to , otherwise the calculation terminates with an error message.