<UL><LI>Rc = global cutoff, -1 means cutoff of half the shortest box length
<LI>zero or more keyword/value pairs may be appended
<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>
<PRE><I>hartree</I> value = none
<I>dproduct</I> value = none
<I>uhf</I> value = none
<I>free</I> value = none
<I>pbc</I> value = Plen
Plen = periodic width of electron = -1 or positive value (distance units)
<I>fix</I> value = Flen
Flen = fixed width of electron = -1 or positive value (distance units)
<I>harm</I> value = width
width = harmonic width constraint
<I>ermscale</I> value = factor
factor = scaling between electron mass and width variable mass
<I>flex_press</I> value = none
</PRE>
</UL>
<P><B>Examples:</B>
</P>
<PRE>pair_style awpmd/cut -1
pair_style awpmd/cut 40.0 uhf free
pair_coeff * *
pair_coeff 2 2 20.0
</PRE>
<P><B>Description:</B>
</P>
<P>This pair style contains an implementation of the Antisymmetrized Wave
Packet Molecular Dynamics (AWPMD) method. Need citation here. Need
basic formulas here. Could be links to other documents.
</P>
<P>Rc is the cutoff.
</P>
<P>The pair_style command allows for several optional keywords
to be specified.
</P>
<P>The <I>hartree</I>, <I>dproduct</I>, and <I>uhf</I> keywords specify the form of the
initial trial wave function for the system. If the <I>hartree</I> keyword
is used, then a Hartree multielectron trial wave function is used. If
the <I>dproduct</I> keyword is used, then a trial function which is a
product of two determinants for each spin type is used. If the <I>uhf</I>
keyword is used, then an unrestricted Hartree-Fock trial wave function
is used.
</P>
<P>The <I>free</I>, <I>pbc</I>, and <I>fix</I> keywords specify a width constraint on
the electron wavepackets. If the <I>free</I> keyword is specified, then there is no
constraint. If the <I>pbc</I> keyword is used and <I>Plen</I> is specified as
-1, then the maximum width is half the shortest box length. If <I>Plen</I>
is a positive value, then the value is the maximum width. If the
<I>fix</I> keyword is used and <I>Flen</I> is specified as -1, then electrons
have a constant width that is read from the data file. If <I>Flen</I> is a
positive value, then the constant width for all electrons is set to
<I>Flen</I>.
</P>
<P>The <I>harm</I> keyword allow oscillations in the width of the
electron wavepackets. More details are needed.
</P>
<P>The <I>ermscale</I> keyword specifies a unitless scaling factor
between the electron masses and the width variable mass. More
details needed.
</P>
<P>If the <I>flex_press</I> keyword is used, then a contribution from the
electrons is added to the total virial and pressure of the system.
</P>
<P>This potential is designed to be used with <AHREF ="atom_style.html">atom_style
wavepacket</A> definitions, in order to handle the
description of systems with interacting nuclei and explicit electrons.
</P>
<P>The following coefficients must be defined for each pair of atoms
types via the <AHREF ="pair_coeff.html">pair_coeff</A> command as in the examples
above, or in the data file or restart files read by the
<AHREF ="read_data.html">read_data</A> or <AHREF ="read_restart.html">read_restart</A>
commands, or by mixing as described below:
</P>
<UL><LI>cutoff (distance units)
</UL>
<P>For <I>awpmd/cut</I>, the cutoff coefficient is optional. If it is not
used (as in some of the examples above), the default global value