SPRING V0: Difference between revisions

From VASP Wiki
No edit summary
No edit summary
Line 1: Line 1:
{{DISPLAYTITLE:SPRING_V0}}
{{DISPLAYTITLE:SPRING_V0}}
{{TAGDEF|SPRING_V0|[real (array)]}}
{{TAGDEF|SPRING_V0|[real (array)]}}
{{DEF|SPRING_V0|0|for all coordinates with <code>status{{=}}8</code> in {{FILE|ICONST}}.}}


Description: Consider the bias potential of the form:
Description: Rate at which the bias potential is shifted in <math>uc/fs</math>.
----
Consider the bias potential for a [[:Category:Molecular dynamics|molecular-dynamics]] (MD) run 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_8}\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>). The coordinates are defined in the {{FILE|ICONST}} file by setting the <code>status=8</code>.
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>


Line 18: Line 21:
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...).
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.
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.


== Related tags and articles ==
== Related tags and articles ==
{{TAG|SPRING_K}}
{{TAG|SPRING_K}},
{{TAG|SPRING_R0}}
{{TAG|SPRING_R0}},
{{FILE|ICONST}}
{{FILE|ICONST}},
{{TAG|Biased molecular dynamics}}
{{TAG|Biased molecular dynamics}}
----
[[Category:Molecular dynamics]][[Category:Biased molecular dynamics]]

Revision as of 06:58, 24 April 2023

SPRING_V0 = [real (array)] 

Default: SPRING_V0 = 0 for all coordinates with status=8 in ICONST.

Description: Rate at which the bias potential is shifted in .


Consider the bias potential for a molecular-dynamics (MD) run of the form:

where the sum runs over all () coordinates the potential acts upon (). The coordinates are defined in the ICONST file by setting the status=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.

Related tags and articles

SPRING_K, SPRING_R0, ICONST, Biased molecular dynamics