SPRING_K

SPRING_K = [real (array)]

Description: Force constant for harmonic bias potential.

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

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