forked from lijiext/lammps
138 lines
4.3 KiB
Plaintext
138 lines
4.3 KiB
Plaintext
.. index:: pair_style awpmd/cut
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pair_style awpmd/cut command
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============================
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Syntax
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""""""
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.. parsed-literal::
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pair_style awpmd/cut Rc keyword value ...
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* Rc = global cutoff, -1 means cutoff of half the shortest box length
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* zero or more keyword/value pairs may be appended
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* keyword = *hartree* or *dproduct* or *uhf* or *free* or *pbc* or *fix* or *harm* or *ermscale* or *flex_press*
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.. parsed-literal::
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*hartree* value = none
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*dproduct* value = none
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*uhf* value = none
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*free* value = none
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*pbc* value = Plen
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Plen = periodic width of electron = -1 or positive value (distance units)
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*fix* value = Flen
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Flen = fixed width of electron = -1 or positive value (distance units)
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*harm* value = width
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width = harmonic width constraint
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*ermscale* value = factor
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factor = scaling between electron mass and width variable mass
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*flex_press* value = none
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Examples
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""""""""
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.. parsed-literal::
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pair_style awpmd/cut -1
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pair_style awpmd/cut 40.0 uhf free
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pair_coeff * *
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pair_coeff 2 2 20.0
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Description
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"""""""""""
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This pair style contains an implementation of the Antisymmetrized Wave
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Packet Molecular Dynamics (AWPMD) method. Need citation here. Need
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basic formulas here. Could be links to other documents.
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Rc is the cutoff.
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The pair_style command allows for several optional keywords
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to be specified.
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The *hartree*\ , *dproduct*\ , and *uhf* keywords specify the form of the
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initial trial wave function for the system. If the *hartree* keyword
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is used, then a Hartree multielectron trial wave function is used. If
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the *dproduct* keyword is used, then a trial function which is a
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product of two determinants for each spin type is used. If the *uhf*
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keyword is used, then an unrestricted Hartree-Fock trial wave function
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is used.
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The *free*\ , *pbc*\ , and *fix* keywords specify a width constraint on
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the electron wavepackets. If the *free* keyword is specified, then there is no
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constraint. If the *pbc* keyword is used and *Plen* is specified as
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-1, then the maximum width is half the shortest box length. If *Plen*
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is a positive value, then the value is the maximum width. If the
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*fix* keyword is used and *Flen* is specified as -1, then electrons
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have a constant width that is read from the data file. If *Flen* is a
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positive value, then the constant width for all electrons is set to
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*Flen*\ .
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The *harm* keyword allow oscillations in the width of the
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electron wavepackets. More details are needed.
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The *ermscale* keyword specifies a unitless scaling factor
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between the electron masses and the width variable mass. More
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details needed.
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If the *flex_press* keyword is used, then a contribution from the
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electrons is added to the total virial and pressure of the system.
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This potential is designed to be used with :doc:`atom_style wavepacket <atom_style>` definitions, in order to handle the
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description of systems with interacting nuclei and explicit electrons.
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The following coefficients must be defined for each pair of atoms
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types via the :doc:`pair_coeff <pair_coeff>` command as in the examples
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above, or in the data file or restart files read by the
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:doc:`read_data <read_data>` or :doc:`read_restart <read_restart>`
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commands, or by mixing as described below:
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* cutoff (distance units)
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For *awpmd/cut*\ , the cutoff coefficient is optional. If it is not
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used (as in some of the examples above), the default global value
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specified in the pair_style command is used.
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----------
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**Mixing, shift, table, tail correction, restart, rRESPA info**\ :
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The :doc:`pair_modify <pair_modify>` mix, shift, table, and tail options
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are not relevant for this pair style.
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This pair style writes its information to :doc:`binary restart files <restart>`, so pair_style and pair_coeff commands do not need
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to be specified in an input script that reads a restart file.
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This pair style can only be used via the *pair* keyword of the
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:doc:`run_style respa <run_style>` command. It does not support the
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*inner*\ , *middle*\ , *outer* keywords.
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----------
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Restrictions
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""""""""""""
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none
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Related commands
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""""""""""""""""
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:doc:`pair_coeff <pair_coeff>`
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Default
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"""""""
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These are the defaults for the pair_style keywords: *hartree* for the
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initial wavefunction, *free* for the wavepacket width.
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.. _lws: http://lammps.sandia.gov
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.. _ld: Manual.html
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.. _lc: Section_commands.html#comm
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