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update docs

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This commit is contained in:
Axel Kohlmeyer
2023-05-31 13:29:48 -04:00
parent cb02563d3d
commit 90000ca166
1 changed files with 13 additions and 9 deletions
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22
doc/src/fix_efield.rst
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@ -28,7 +28,7 @@ Syntax
*energy* value = v_name
v_name = variable with name that calculates the potential energy of each atom in the added E-field
*potential* value = v_name
v_name = variable with name that calculates the electric potential of each atom in the added E-field (overrides *energy*)
v_name = variable with name that calculates the electric potential of each atom in the added E-field
Examples
""""""""
@ -136,6 +136,8 @@ due to the electric field were a spring-like F = kx, then the energy
formula should be E = -0.5kx\^2. If you don't do this correctly, the
minimization will not converge properly.
.. versionadded:: TBD
The *potential* keyword can be used as an alternative to the *energy* keyword
to specify the name of an atom-style variable, which is used to compute the
added electric potential to each atom as a function of its position. The
@ -144,14 +146,16 @@ in `units real`, the potential should be in volts). As with the *energy*
keyword, the variable name is specified as "v_name". The energy added by this
fix is then calculated as the electric potential multiplied by charge.
The *potential* keyword is mainly intended for correct charge equilibration
in simulations with :doc:`fix qeq/reaxff<fix_qeq_reaxff>`, since with variable
charges the electric potential can be known beforehand but the energy cannot.
A small additional benefit is that the *energy* keyword requires an additional
conversion to energy units which the *potential* keyword avoids. Thus, when the
*potential* keyword is specified, the *energy* keyword is ignored (the simulation
will proceed but with a warning issued). As with *energy*, the *potential*
keyword is not allowed if the added field is a constant vector.
The *potential* keyword is mainly intended for correct charge
equilibration in simulations with :doc:`fix qeq/reaxff<fix_qeq_reaxff>`,
since with variable charges the electric potential can be known
beforehand but the energy cannot. A small additional benefit is that
the *energy* keyword requires an additional conversion to energy units
which the *potential* keyword avoids. Thus, when the *potential*
keyword is specified, the *energy* keyword must not be used. As with
*energy*, the *potential* keyword is not allowed if the added field is a
constant vector. The *potential* keyword is not supported by *fix
efield/tip4p*.
----------