forked from lijiext/lammps
131 lines
4.8 KiB
HTML
131 lines
4.8 KiB
HTML
<HTML>
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<CENTER><A HREF = "http://lammps.sandia.gov">LAMMPS WWW Site</A> - <A HREF = "Manual.html">LAMMPS Documentation</A> - <A HREF = "Section_commands.html#comm">LAMMPS Commands</A>
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<HR>
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<H3>pair_style awpmd/cut command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>pair_style awpmd/cut Rc keyword value ...
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</PRE>
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<UL><LI>Rc = global cutoff, -1 means cutoff of half the shortest box length
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<LI>zero or more keyword/value pairs may be appended
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<LI>keyword = <I>hartree</I> or <I>dproduct</I> or <I>uhf</I> or <I>free</I> or <I>pbc</I> or <I>fix</I> or <I>harm</I> or <I>ermscale</I> or <I>flex_press</I>
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<PRE> <I>hartree</I> value = none
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<I>dproduct</I> value = none
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<I>uhf</I> value = none
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<I>free</I> value = none
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<I>pbc</I> value = Plen
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Plen = periodic width of electron = -1 or positive value (distance units)
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<I>fix</I> value = Flen
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Flen = fixed width of electron = -1 or positive value (distance units)
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<I>harm</I> value = width
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width = harmonic width constraint
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<I>ermscale</I> value = factor
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factor = scaling between electron mass and width variable mass
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<I>flex_press</I> value = none
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</PRE>
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>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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</PRE>
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<P><B>Description:</B>
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</P>
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<P>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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</P>
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<P>Rc is the cutoff.
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</P>
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<P>The pair_style command allows for several optional keywords
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to be specified.
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</P>
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<P>The <I>hartree</I>, <I>dproduct</I>, and <I>uhf</I> keywords specify the form of the
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initial trial wave function for the system. If the <I>hartree</I> keyword
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is used, then a Hartree multielectron trial wave function is used. If
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the <I>dproduct</I> 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 <I>uhf</I>
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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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</P>
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<P>The <I>free</I>, <I>pbc</I>, and <I>fix</I> keywords specify a width constraint on
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the electron wavepackets. If the <I>free</I> keyword is specified, then there is no
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constraint. If the <I>pbc</I> keyword is used and <I>Plen</I> is specified as
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-1, then the maximum width is half the shortest box length. If <I>Plen</I>
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is a positive value, then the value is the maximum width. If the
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<I>fix</I> keyword is used and <I>Flen</I> is specified as -1, then electrons
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have a constant width that is read from the data file. If <I>Flen</I> is a
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positive value, then the constant width for all electrons is set to
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<I>Flen</I>.
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</P>
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<P>The <I>harm</I> keyword allow oscillations in the width of the
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electron wavepackets. More details are needed.
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</P>
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<P>The <I>ermscale</I> 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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</P>
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<P>If the <I>flex_press</I> 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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</P>
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<P>This potential is designed to be used with <A HREF = "atom_style.html">atom_style
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wavepacket</A> definitions, in order to handle the
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description of systems with interacting nuclei and explicit electrons.
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</P>
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<P>The following coefficients must be defined for each pair of atoms
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types via the <A HREF = "pair_coeff.html">pair_coeff</A> 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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<A HREF = "read_data.html">read_data</A> or <A HREF = "read_restart.html">read_restart</A>
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commands, or by mixing as described below:
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</P>
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<UL><LI>cutoff (distance units)
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</UL>
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<P>For <I>awpmd/cut</I>, 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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</P>
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<HR>
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<P><B>Mixing, shift, table, tail correction, restart, rRESPA info</B>:
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</P>
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<P>The <A HREF = "pair_modify.html">pair_modify</A> mix, shift, table, and tail options
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are not relevant for this pair style.
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</P>
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<P>This pair style writes its information to <A HREF = "restart.html">binary restart
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files</A>, 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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</P>
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<P>This pair style can only be used via the <I>pair</I> keyword of the
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<A HREF = "run_style.html">run_style respa</A> command. It does not support the
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<I>inner</I>, <I>middle</I>, <I>outer</I> keywords.
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</P>
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<HR>
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<P><B>Restrictions:</B> none
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</P>
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<P><B>Related commands:</B>
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</P>
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<P><A HREF = "pair_coeff.html">pair_coeff</A>
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</P>
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<P><B>Default:</B>
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</P>
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<P>These are the defaults for the pair_style keywords: <I>hartree</I> for the
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initial wavefunction, <I>free</I> for the wavepacket width.
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</P>
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</HTML>
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