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58
doc/pair_coul.html
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@ -41,6 +41,8 @@
</H3> </H3>
<H3>pair_style coul/msm/omp command <H3>pair_style coul/msm/omp command
</H3> </H3>
<H3>pair_style coul/streitz command
</H3>
<H3>pair_style coul/wolf command <H3>pair_style coul/wolf command
</H3> </H3>
<H3>pair_style coul/wolf/kk command <H3>pair_style coul/wolf/kk command
@ -63,6 +65,7 @@ pair_style coul/dsf alpha cutoff
pair_style coul/long cutoff pair_style coul/long cutoff
pair_style coul/long/gpu cutoff pair_style coul/long/gpu cutoff
pair_style coul/wolf alpha cutoff pair_style coul/wolf alpha cutoff
pair_style coul/streitz cutoff keyword alpha
pair_style tip4p/cut otype htype btype atype qdist cutoff pair_style tip4p/cut otype htype btype atype qdist cutoff
pair_style tip4p/long otype htype btype atype qdist cutoff pair_style tip4p/long otype htype btype atype qdist cutoff
</PRE> </PRE>
@ -92,6 +95,10 @@ pair_coeff * *
<PRE>pair_style coul/wolf 0.2 9.0 <PRE>pair_style coul/wolf 0.2 9.0
pair_coeff * * pair_coeff * *
</PRE> </PRE>
<PRE>pair_style coul/streitz 12.0 ewald
pair_style coul/streitz 12.0 wolf 0.30
pair_coeff * * AlO.streitz Al O
</PRE>
<PRE>pair_style tip4p/cut 1 2 7 8 0.15 12.0 <PRE>pair_style tip4p/cut 1 2 7 8 0.15 12.0
pair_coeff * * pair_coeff * *
</PRE> </PRE>
@ -110,6 +117,8 @@ the 2 atoms, and epsilon is the dielectric constant which can be set
by the <A HREF = "dielectric.html">dielectric</A> command. The cutoff Rc truncates by the <A HREF = "dielectric.html">dielectric</A> command. The cutoff Rc truncates
the interaction distance. the interaction distance.
</P> </P>
<HR>
<P>Style <I>coul/debye</I> adds an additional exp() damping factor to the <P>Style <I>coul/debye</I> adds an additional exp() damping factor to the
Coulombic term, given by Coulombic term, given by
</P> </P>
@ -118,6 +127,8 @@ Coulombic term, given by
<P>where kappa is the Debye length. This potential is another way to <P>where kappa is the Debye length. This potential is another way to
mimic the screening effect of a polar solvent. mimic the screening effect of a polar solvent.
</P> </P>
<HR>
<P>Style <I>coul/dsf</I> computes Coulombic interactions via the damped <P>Style <I>coul/dsf</I> computes Coulombic interactions via the damped
shifted force model described in <A HREF = "#Fennell">Fennell</A>, given by: shifted force model described in <A HREF = "#Fennell">Fennell</A>, given by:
</P> </P>
@ -129,6 +140,8 @@ Wolf model (described below) to provide consistent forces and energies
(the Wolf potential is not differentiable at the cutoff) and smooth (the Wolf potential is not differentiable at the cutoff) and smooth
decay to zero. decay to zero.
</P> </P>
<HR>
<P>Style <I>coul/wolf</I> computes Coulombic interactions via the Wolf <P>Style <I>coul/wolf</I> computes Coulombic interactions via the Wolf
summation method, described in <A HREF = "#Wolf">Wolf</A>, given by: summation method, described in <A HREF = "#Wolf">Wolf</A>, given by:
</P> </P>
@ -147,6 +160,46 @@ forces calcluated by the Wolf summation method approach those of the
Ewald sum. So it is a means of getting effective long-range Ewald sum. So it is a means of getting effective long-range
interactions with a short-range potential. interactions with a short-range potential.
</P> </P>
<HR>
<P>Style <I>coul/streitz</I> is the Coulomb pair interaction defined as part
of the Streitz-Mintmire potential, as described in <A HREF = "#Streitz">this
paper</A>, in which charge distribution about an atom is modeled
as a Slater 1<I>s</I> orbital. More details can be found in the referenced
paper. To fully reproduce the published Streitz-Mintmire potential,
which is a variable charge potential, style <I>coul/streitz</I> must be
used with <A HREF = "pair_eam.html">pair_style eam/alloy</A> via the <A HREF = "pair_hybrid.html">pair_style
hybrid/overlay</A> command and charge equilibration must
be performed via the <A HREF = "fix_qeq.html">fix qeq/slater</A> command. For
example:
</P>
<PRE>pair_style hybrid/overlay coul/streitz 12.0 wolf 0.31 eam/alloy
pair_coeff * * coul/streitz AlO.streitz Al O
pair_coeff * * eam/alloy AlO.eam.alloy Al O
fix 1 all qeq/slater 1 12.0 1.0e-6 100 coul/streitz
</PRE>
<P>The keyword <I>wolf</I> after the 12.0 <I>cutoff</I> denotes computing Coulombic
interactions via Wolf summation. An additional damping parameter is
required for the Wolf summation, as described for the coul/wolf
potential above. Alternatively, Coulombic interactions can be
computed via an Ewald summation. For example:
</P>
<PRE>pair_style hybrid/overlay coul/streitz 12.0 ewald eam/alloy
kspace_style ewald 1e-6
</PRE>
<P>Keyword <I>ewald</I> does not need a damping parameter, but a
<A HREF = "kspace_style.html">kspace_style</A> must be defined. The Ewald summation
option was the method used in Streitz and Mintmire's original paper,
but a Wolf summation offers a speed-up in some cases.
</P>
<P>For the fix qeq/slater command, the <I>qfile</I> can be a filename that
contains QEq parameters as discussed on the <A HREF = "fix_qeq.html">fix qeq</A>
command doc page. Alternatively <I>qfile</I> can be replaced by
"coul/streitz", in which case the fix will extract QEq parameters from
the coul/streitz pair style itself.
</P>
<HR>
<P>Styles <I>coul/long</I> and <I>coul/msm</I> compute the same Coulombic <P>Styles <I>coul/long</I> and <I>coul/msm</I> compute the same Coulombic
interactions as style <I>coul/cut</I> except that an additional damping interactions as style <I>coul/cut</I> except that an additional damping
factor is applied so it can be used in conjunction with the factor is applied so it can be used in conjunction with the
@ -285,4 +338,9 @@ Phys, 110, 8254 (1999).
<P><B>(Fennell)</B> C. J. Fennell, J. D. Gezelter, J Chem Phys, 124, <P><B>(Fennell)</B> C. J. Fennell, J. D. Gezelter, J Chem Phys, 124,
234104 (2006). 234104 (2006).
</P> </P>
<A NAME = "Streitz"></A>
<P><B>(Streitz)</B> F. H. Streitz, J. W. Minimire, Phys Rev B 50,
11996-12003 (1994).
</P>
</HTML> </HTML>

56
doc/pair_coul.txt
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@ -22,6 +22,7 @@ pair_style coul/long/omp command :h3
pair_style coul/long/gpu command :h3 pair_style coul/long/gpu command :h3
pair_style coul/msm command :h3 pair_style coul/msm command :h3
pair_style coul/msm/omp command :h3 pair_style coul/msm/omp command :h3
pair_style coul/streitz command :h3
pair_style coul/wolf command :h3 pair_style coul/wolf command :h3
pair_style coul/wolf/kk command :h3 pair_style coul/wolf/kk command :h3
pair_style coul/wolf/omp command :h3 pair_style coul/wolf/omp command :h3
@ -38,6 +39,7 @@ pair_style coul/dsf alpha cutoff
pair_style coul/long cutoff pair_style coul/long cutoff
pair_style coul/long/gpu cutoff pair_style coul/long/gpu cutoff
pair_style coul/wolf alpha cutoff pair_style coul/wolf alpha cutoff
pair_style coul/streitz cutoff keyword alpha
pair_style tip4p/cut otype htype btype atype qdist cutoff pair_style tip4p/cut otype htype btype atype qdist cutoff
pair_style tip4p/long otype htype btype atype qdist cutoff :pre pair_style tip4p/long otype htype btype atype qdist cutoff :pre
@ -67,6 +69,10 @@ pair_coeff * * :pre
pair_style coul/wolf 0.2 9.0 pair_style coul/wolf 0.2 9.0
pair_coeff * * :pre pair_coeff * * :pre
pair_style coul/streitz 12.0 ewald
pair_style coul/streitz 12.0 wolf 0.30
pair_coeff * * AlO.streitz Al O :pre
pair_style tip4p/cut 1 2 7 8 0.15 12.0 pair_style tip4p/cut 1 2 7 8 0.15 12.0
pair_coeff * * :pre pair_coeff * * :pre
@ -85,6 +91,8 @@ the 2 atoms, and epsilon is the dielectric constant which can be set
by the "dielectric"_dielectric.html command. The cutoff Rc truncates by the "dielectric"_dielectric.html command. The cutoff Rc truncates
the interaction distance. the interaction distance.
:line
Style {coul/debye} adds an additional exp() damping factor to the Style {coul/debye} adds an additional exp() damping factor to the
Coulombic term, given by Coulombic term, given by
@ -93,6 +101,8 @@ Coulombic term, given by
where kappa is the Debye length. This potential is another way to where kappa is the Debye length. This potential is another way to
mimic the screening effect of a polar solvent. mimic the screening effect of a polar solvent.
:line
Style {coul/dsf} computes Coulombic interactions via the damped Style {coul/dsf} computes Coulombic interactions via the damped
shifted force model described in "Fennell"_#Fennell, given by: shifted force model described in "Fennell"_#Fennell, given by:
@ -104,6 +114,8 @@ Wolf model (described below) to provide consistent forces and energies
(the Wolf potential is not differentiable at the cutoff) and smooth (the Wolf potential is not differentiable at the cutoff) and smooth
decay to zero. decay to zero.
:line
Style {coul/wolf} computes Coulombic interactions via the Wolf Style {coul/wolf} computes Coulombic interactions via the Wolf
summation method, described in "Wolf"_#Wolf, given by: summation method, described in "Wolf"_#Wolf, given by:
@ -122,6 +134,46 @@ forces calcluated by the Wolf summation method approach those of the
Ewald sum. So it is a means of getting effective long-range Ewald sum. So it is a means of getting effective long-range
interactions with a short-range potential. interactions with a short-range potential.
:line
Style {coul/streitz} is the Coulomb pair interaction defined as part
of the Streitz-Mintmire potential, as described in "this
paper"_#Streitz, in which charge distribution about an atom is modeled
as a Slater 1{s} orbital. More details can be found in the referenced
paper. To fully reproduce the published Streitz-Mintmire potential,
which is a variable charge potential, style {coul/streitz} must be
used with "pair_style eam/alloy"_pair_eam.html via the "pair_style
hybrid/overlay"_pair_hybrid.html command and charge equilibration must
be performed via the "fix qeq/slater"_fix_qeq.html command. For
example:
pair_style hybrid/overlay coul/streitz 12.0 wolf 0.31 eam/alloy
pair_coeff * * coul/streitz AlO.streitz Al O
pair_coeff * * eam/alloy AlO.eam.alloy Al O
fix 1 all qeq/slater 1 12.0 1.0e-6 100 coul/streitz :pre
The keyword {wolf} after the 12.0 {cutoff} denotes computing Coulombic
interactions via Wolf summation. An additional damping parameter is
required for the Wolf summation, as described for the coul/wolf
potential above. Alternatively, Coulombic interactions can be
computed via an Ewald summation. For example:
pair_style hybrid/overlay coul/streitz 12.0 ewald eam/alloy
kspace_style ewald 1e-6 :pre
Keyword {ewald} does not need a damping parameter, but a
"kspace_style"_kspace_style.html must be defined. The Ewald summation
option was the method used in Streitz and Mintmire's original paper,
but a Wolf summation offers a speed-up in some cases.
For the fix qeq/slater command, the {qfile} can be a filename that
contains QEq parameters as discussed on the "fix qeq"_fix_qeq.html
command doc page. Alternatively {qfile} can be replaced by
"coul/streitz", in which case the fix will extract QEq parameters from
the coul/streitz pair style itself.
:line
Styles {coul/long} and {coul/msm} compute the same Coulombic Styles {coul/long} and {coul/msm} compute the same Coulombic
interactions as style {coul/cut} except that an additional damping interactions as style {coul/cut} except that an additional damping
factor is applied so it can be used in conjunction with the factor is applied so it can be used in conjunction with the
@ -257,3 +309,7 @@ Phys, 110, 8254 (1999).
:link(Fennell) :link(Fennell)
[(Fennell)] C. J. Fennell, J. D. Gezelter, J Chem Phys, 124, [(Fennell)] C. J. Fennell, J. D. Gezelter, J Chem Phys, 124,
234104 (2006). 234104 (2006).
:link(Streitz)
[(Streitz)] F. H. Streitz, J. W. Minimire, Phys Rev B 50,
11996-12003 (1994).