SPRING K

SPRING_K = [real (array)] 

Description: Force constant for harmonic bias potential.

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The parameter SPRING_K defines force constants ([math]\displaystyle{ \kappa_{\mu} }[/math]) for the harmonic bias of the following 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. The units of [math]\displaystyle{ \kappa_{\mu} }[/math] are [math]\displaystyle{ eV/uc }[/math] where [math]\displaystyle{ uc }[/math] units of 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_K must be equal to [math]\displaystyle{ M_8 }[/math], otherwise the calculation terminates with an error message.

Related tags and articles

SPRING_R0, SPRING_V0, ICONST, Biased molecular dynamics

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