SPRING V0: Difference between revisions

Revision as of 08:42, 11 April 2023

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.

@@ Line 7: / Line 7: @@
 </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.
-Optionally, the position of minimum (<math>\xi_{0\mu}</math>) can be shifted at a constant rate <math>\dot{\xi}_{\mu}</math>, 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>
-\xi_{0\mu}(t+\Delta t) = \xi_{0\mu}(t)\dot{\xi}_{\mu}(q) \;
+\xi_{0\mu}(t+\Delta t) = \xi_{0\mu}(t) + \dot{\xi}_{\mu}(q)\Delta t \;
 </math>
+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 parameter {{TAG|SPRING_V0}} defines the rate at which the position of minimum (<math>\xi_{0\mu}</math>) of the harmonic bias potential of the form:
-<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 \;
-</math>
-is shifted,
-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.
-The units of {{TAG|SPRING_V0}} 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 number of items defined via {{TAG|SPRING_V0}} must be equal to <math>M_8</math>, otherwise the calculation terminates with an error message.

Revision as of 08:42, 11 April 2023

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