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# Difference between revisions of "SCALEE"

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{{TAGDEF|SCALEE|[real]|1}} | {{TAGDEF|SCALEE|[real]|1}} | ||

− | Description: This tag specifies the scaling of the energies and forces. | + | Description: This tag specifies the scaling constant of the energies and forces. |

---- | ---- | ||

+ | In thermodynamic integration the free energy difference between two systems is defined as | ||

+ | |||

+ | <math> \Delta F = \int\limits_{0}^{1} d\lambda \langle U_{1} - U_{0} \rangle </math> | ||

+ | |||

+ | where | ||

+ | |||

+ | |||

For thermodynamic integration this parameter controls the coupling parameter <math>\lambda</math>. | For thermodynamic integration this parameter controls the coupling parameter <math>\lambda</math>. | ||

## Revision as of 08:59, 31 March 2020

SCALEE = [real]

Default: **SCALEE** = 1

Description: This tag specifies the scaling constant of the energies and forces.

In thermodynamic integration the free energy difference between two systems is defined as

where

For thermodynamic integration this parameter controls the coupling parameter .

This parameter is only used if SCALEE1.

Usually the thermodynamic integration is carried out from the ideal gas to the liquid state.

If the file DYNMATFULL exists in the calculation directory (from a previous calculation using PHON_NSTRUCT=-1) and SCALEE1, the second order Hessian matrix is added to the force and thermodynamic integration from a harmonic model to a fully interacting system is carried out. Here the Hamiltonian for a certain integration point along the thermodynamic integration pathway is given as

## Related Tags and Sections

VCAIMAGES, IMAGES, NCORE IN IMAGE1, PHON_NSTRUCT