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
@@ -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.
-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) 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.
-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. diff --git a/doc/pair_modify.txt b/doc/pair_modify.txt index 2614e93db2..88e2151f94 100644 --- a/doc/pair_modify.txt +++ b/doc/pair_modify.txt @@ -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.