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git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@9592 f3b2605a-c512-4ea7-a41b-209d697bcdaa

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31
doc/pair_modify.html
View File

@ -17,14 +17,18 @@
</PRE>
<UL><LI>one or more keyword/value pairs may be listed
<LI>keyword = <I>shift</I> or <I>mix</I> or <I>table</I> or <I>tabinner</I> or <I>tail</I> or <I>compute</I>
<LI>keyword = <I>shift</I> or <I>mix</I> or <I>table</I> or <I>table/disp</I> or <I>tabinner</I> or <I>tabinner/disp</I> or <I>tail</I> or <I>compute</I>
<PRE> <I>mix</I> value = <I>geometric</I> or <I>arithmetic</I> or <I>sixthpower</I>
<I>shift</I> value = <I>yes</I> or <I>no</I>
<I>table</I> value = N
2^N = # of values in table
<I>table/disp</I> value = N
2^N = # of values in table
<I>tabinner</I> value = cutoff
cutoff = inner cutoff at which to begin table (distance units)
<I>tabinner/disp</I> value = cutoff
cutoff = inner cutoff at which to begin table (distance units)
<I>tail</I> value = <I>yes</I> or <I>no</I>
<I>compute</I> value = <I>yes</I> or <I>no</I>
</PRE>
@ -82,9 +86,10 @@ output, but does not affect pair forces or atom trajectories. See the
doc page for individual pair styles to see which ones support this
option.
</P>
<P>The <I>table</I> keyword applies to pair styles with a long-range Coulombic
term; see the doc page for individual styles to see which potentials
support this option. If N is non-zero, a table of length 2^N is
<P>The <I>table</I> and <I>table/disp</I> keywords apply to pair styles with a
long-range Coulombic term or long-range dispersion term respectively;
see the doc page for individual styles to see which potentials support
these options. If N is non-zero, a table of length 2^N is
pre-computed for forces and energies, which can shrink their
computational cost by up to a factor of 2. The table is indexed via a
bit-mapping technique <A HREF = "#Wolff">(Wolff)</A> and a linear interpolation is
@ -103,14 +108,16 @@ evaluation, which is what earlier versions of LAMMPS did. Values
greater than 16 typically slow down the simulation and will not
improve accuracy; values from 1 to 8 give unreliable results.
</P>
<P>The <I>tabinner</I> keyword sets an inner cutoff above which the pairwise
computation is done by table lookup (if tables are invoked). The
smaller this value is set, the less accurate the table becomes (for a
given number of table values), which can require use of larger tables.
The default cutoff value is sqrt(2.0) distance units which means
nearly all pairwise interactions are computed via table lookup for
simulations with "real" units, but some close pairs may be computed
directly (non-table) for simulations with "lj" units.
<P>The <I>tabinner</I> and <I>tabinner/disp</I> keywords set an inner cutoff above
which the pairwise computation is done by table lookup (if tables are
invoked), for the corresponding Coulombic and dispersion tables
discussed with the <I>table</I> and <I>table/disp</I> keywords. The smaller the
cutoff is set, the less accurate the table becomes (for a given number
of table values), which can require use of larger tables. The default
cutoff value is sqrt(2.0) distance units which means nearly all
pairwise interactions are computed via table lookup for simulations
with "real" units, but some close pairs may be computed directly
(non-table) for simulations with "lj" units.
</P>
<P>When the <I>tail</I> keyword is set to <I>yes</I>, certain pair styles will add
a long-range VanderWaals tail "correction" to the energy and pressure.

31
doc/pair_modify.txt
View File

@ -13,13 +13,17 @@ pair_modify command :h3
pair_modify keyword value ... :pre
one or more keyword/value pairs may be listed :ulb,l
keyword = {shift} or {mix} or {table} or {tabinner} or {tail} or {compute} :l
keyword = {shift} or {mix} or {table} or {table/disp} or {tabinner} or {tabinner/disp} or {tail} or {compute} :l
{mix} value = {geometric} or {arithmetic} or {sixthpower}
{shift} value = {yes} or {no}
{table} value = N
2^N = # of values in table
{table/disp} value = N
2^N = # of values in table
{tabinner} value = cutoff
cutoff = inner cutoff at which to begin table (distance units)
{tabinner/disp} value = cutoff
cutoff = inner cutoff at which to begin table (distance units)
{tail} value = {yes} or {no}
{compute} value = {yes} or {no} :pre
:ule
@ -76,9 +80,10 @@ output, but does not affect pair forces or atom trajectories. See the
doc page for individual pair styles to see which ones support this
option.
The {table} keyword applies to pair styles with a long-range Coulombic
term; see the doc page for individual styles to see which potentials
support this option. If N is non-zero, a table of length 2^N is
The {table} and {table/disp} keywords apply to pair styles with a
long-range Coulombic term or long-range dispersion term respectively;
see the doc page for individual styles to see which potentials support
these options. If N is non-zero, a table of length 2^N is
pre-computed for forces and energies, which can shrink their
computational cost by up to a factor of 2. The table is indexed via a
bit-mapping technique "(Wolff)"_#Wolff and a linear interpolation is
@ -97,14 +102,16 @@ evaluation, which is what earlier versions of LAMMPS did. Values
greater than 16 typically slow down the simulation and will not
improve accuracy; values from 1 to 8 give unreliable results.
The {tabinner} keyword sets an inner cutoff above which the pairwise
computation is done by table lookup (if tables are invoked). The
smaller this value is set, the less accurate the table becomes (for a
given number of table values), which can require use of larger tables.
The default cutoff value is sqrt(2.0) distance units which means
nearly all pairwise interactions are computed via table lookup for
simulations with "real" units, but some close pairs may be computed
directly (non-table) for simulations with "lj" units.
The {tabinner} and {tabinner/disp} keywords set an inner cutoff above
which the pairwise computation is done by table lookup (if tables are
invoked), for the corresponding Coulombic and dispersion tables
discussed with the {table} and {table/disp} keywords. The smaller the
cutoff is set, the less accurate the table becomes (for a given number
of table values), which can require use of larger tables. The default
cutoff value is sqrt(2.0) distance units which means nearly all
pairwise interactions are computed via table lookup for simulations
with "real" units, but some close pairs may be computed directly
(non-table) for simulations with "lj" units.
When the {tail} keyword is set to {yes}, certain pair styles will add
a long-range VanderWaals tail "correction" to the energy and pressure.