107 lines
3.2 KiB
ReStructuredText
107 lines
3.2 KiB
ReStructuredText
.. index:: angle_coeff
|
|
|
|
angle_coeff command
|
|
===================
|
|
|
|
Syntax
|
|
""""""
|
|
|
|
.. code-block:: LAMMPS
|
|
|
|
angle_coeff N args
|
|
|
|
* N = numeric angle type (see asterisk form below), or type label
|
|
* args = coefficients for one or more angle types
|
|
|
|
Examples
|
|
""""""""
|
|
|
|
.. code-block:: LAMMPS
|
|
|
|
angle_coeff 1 300.0 107.0
|
|
angle_coeff * 5.0
|
|
angle_coeff 2*10 5.0
|
|
|
|
labelmap angle 1 hydroxyl
|
|
angle_coeff hydroxyl 300.0 107.0
|
|
|
|
Description
|
|
"""""""""""
|
|
|
|
Specify the angle force field coefficients for one or more angle types.
|
|
The number and meaning of the coefficients depends on the angle style.
|
|
Angle coefficients can also be set in the data file read by the
|
|
:doc:`read_data <read_data>` command or in a restart file.
|
|
|
|
:math:`N` can be specified in one of two ways. An explicit numeric
|
|
value can be used, as in the first example above. Or :math:`N` can be a
|
|
type label, which is an alphanumeric string defined by the
|
|
:doc:`labelmap <labelmap>` command or in a section of a data file read
|
|
by the :doc:`read_data <read_data>` command.
|
|
|
|
For numeric values only, a wild-card asterisk can be used to set the
|
|
coefficients for multiple angle types. This takes the form "\*" or
|
|
"\*n" or "n\*" or "m\*n". If :math:`N` is the number of angle types,
|
|
then an asterisk with no numeric values means all types from 1 to
|
|
:math:`N`. A leading asterisk means all types from 1 to n (inclusive).
|
|
A trailing asterisk means all types from n to :math:`N` (inclusive). A
|
|
middle asterisk means all types from m to n (inclusive).
|
|
|
|
Note that using an :doc:`angle_coeff <angle_coeff>` command can
|
|
override a previous setting for the same angle type. For example,
|
|
these commands set the coeffs for all angle types, then overwrite the
|
|
coeffs for just angle type 2:
|
|
|
|
.. code-block:: LAMMPS
|
|
|
|
angle_coeff * 200.0 107.0 1.2
|
|
angle_coeff 2 50.0 107.0
|
|
|
|
A line in a data file that specifies angle coefficients uses the exact
|
|
same format as the arguments of the :doc:`angle_coeff <angle_coeff>`
|
|
command in an input script, except that wild-card asterisks should not
|
|
be used since coefficients for all :math:`N` types must be listed in the
|
|
file. For example, under the "Angle Coeffs" section of a data file, the
|
|
line that corresponds to the first example above would be listed as
|
|
|
|
.. parsed-literal::
|
|
|
|
1 300.0 107.0
|
|
|
|
The :doc:`angle_style class2 <angle_class2>` is an exception to this
|
|
rule, in that an additional argument is used in the input script to
|
|
allow specification of the cross-term coefficients. See its doc page
|
|
for details.
|
|
|
|
----------
|
|
|
|
The list of all angle styles defined in LAMMPS is given on the
|
|
:doc:`angle_style <angle_style>` doc page. They are also listed in more
|
|
compact form on the :ref:`Commands angle <angle>` doc page.
|
|
|
|
On either of those pages, click on the style to display the formula it
|
|
computes and its coefficients as specified by the associated
|
|
:doc:`angle_coeff <angle_coeff>` command.
|
|
|
|
----------
|
|
|
|
Restrictions
|
|
""""""""""""
|
|
|
|
This command must come after the simulation box is defined by a
|
|
:doc:`read_data <read_data>`, :doc:`read_restart <read_restart>`, or
|
|
:doc:`create_box <create_box>` command.
|
|
|
|
An angle style must be defined before any angle coefficients are
|
|
set, either in the input script or in a data file.
|
|
|
|
Related commands
|
|
""""""""""""""""
|
|
|
|
:doc:`angle_style <angle_style>`
|
|
|
|
Default
|
|
"""""""
|
|
|
|
none
|