+These are accelerated pair styles, which can be used if LAMMPS is diff --git a/doc/Section_commands.txt b/doc/Section_commands.txt index e30d5af4a8..021d209e45 100644 --- a/doc/Section_commands.txt +++ b/doc/Section_commands.txt @@ -801,6 +801,7 @@ package"_Section_start.html#start_3. "lj/sf"_pair_lj_sf.html, "meam/spline"_pair_meam_spline.html, "meam/sw/spline"_pair_meam_sw_spline.html, +"nb3b/harmonic"_pair_nb3b_harmonic.html, "reax/c"_pair_reax_c.html, "sph/heatconduction"_pair_sph_heatconduction.html, "sph/idealgas"_pair_sph_idealgas.html, diff --git a/doc/pair_nb3b_harmonic.html b/doc/pair_nb3b_harmonic.html new file mode 100644 index 0000000000..c210f4d01d --- /dev/null +++ b/doc/pair_nb3b_harmonic.html @@ -0,0 +1,104 @@ + +
Syntax: +
+pair_style nb3b/harmonic ++
Examples: +
+pair_style nb3b/harmonic +pair_coeff * * MgOH.nb3bharmonic Mg O H ++
Description: +
+This pair style computes a nonbonded 3-body harmonic potential for the +energy E of a system of atoms as +
+
+where theta_0 is the equilibrium value of the angle and K is a +prefactor. Note that the usual 1/2 factor is included in K. The form +of the potential is identical to that used in angle_style harmonic, +but in this case, the atoms do not need to be explicitly bonded. +
+Only a single pair_coeff command is used with this style which +specifies a potential file with parameters for specified elements. +These are mapped to LAMMPS atom types by specifying N additional +arguments after the filename in the pair_coeff command, where N is the +number of LAMMPS atom types: +
+See the pair_coeff doc page for alternate ways +to specify the path for the potential file. +
+As an example, imagine a file SiC.nb3bharmonic has potential values +for Si and C. If your LAMMPS simulation has 4 atoms types and you +want the 1st 3 to be Si, and the 4th to be C, you would use the +following pair_coeff command: +
+pair_coeff * * SiC.nb3bharmonic Si Si Si C ++
The 1st 2 arguments must be * * so as to span all LAMMPS atom types. +The first three Si arguments map LAMMPS atom types 1,2,3 to the Si +element in the potential file. The final C argument maps LAMMPS atom +type 4 to the C element in the potential file. If a mapping value is +specified as NULL, the mapping is not performed. This can be used +when the potential is used as part of the hybrid pair style. The +NULL values are placeholders for atom types that will be used with +other potentials. An example of a pair_coeff command for use with the +hybrid pair style is: +
+pair_coeff * * 3bnbharm MgOH.3bnbharm Mg O H +
+Three-body nonbonded harmonic files in the potentials directory of +the LAMMPS distribution have a ".nb3bharmonic" suffix. Lines that are +not blank or comments (starting with #) define parameters for a +triplet of elements. +
+Each entry has six arguments. The first three are atom types as +referenced in the LAMMPS input file. The first argument specifies the +central atom. The fourth argument indicates the K parameter. The +fifth argument indicates theta_0. The sixth argument indicates a +separation cutoff in Angstroms. +
+For a given entry, if the second and third arguments are identical, +then the entry is for a cutoff for the distance between types 1 and 2 +(values for K and theta_0 are irrelevant in this case). +
+For a given entry, if the first three arguments are all different, +then the entry is for the K and theta_0 parameters (the cutoff in +this case is irrelevant). +
+It is not required that the potential file contain entries for all +of the elements listed in the pair_coeff command. It can also contain +entries for additional elements not being used in a particular +simulation; LAMMPS ignores those entries. +
+Restrictions: +
+This pair style can only be used if LAMMPS was built with the +USER_MISC package. See the Making LAMMPS +section for more info on packages. +
+Related commands: +
+ +Default: none +
+ diff --git a/doc/pair_nb3b_harmonic.txt b/doc/pair_nb3b_harmonic.txt new file mode 100644 index 0000000000..3f1936cdeb --- /dev/null +++ b/doc/pair_nb3b_harmonic.txt @@ -0,0 +1,99 @@ +"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c + +:link(lws,http://lammps.sandia.gov) +:link(ld,Manual.html) +:link(lc,Section_commands.html#comm) + +:line + +pair_style nb3b/harmonic command :h3 + +[Syntax:] + +pair_style nb3b/harmonic :pre + +[Examples:] + +pair_style nb3b/harmonic +pair_coeff * * MgOH.nb3bharmonic Mg O H :pre + +[Description:] + +This pair style computes a nonbonded 3-body harmonic potential for the +energy E of a system of atoms as + +:c,image(Eqs/pair_3bnbharm.jpg) + +where {theta_0} is the equilibrium value of the angle and {K} is a +prefactor. Note that the usual 1/2 factor is included in {K}. The form +of the potential is identical to that used in angle_style {harmonic}, +but in this case, the atoms do not need to be explicitly bonded. + +Only a single pair_coeff command is used with this style which +specifies a potential file with parameters for specified elements. +These are mapped to LAMMPS atom types by specifying N additional +arguments after the filename in the pair_coeff command, where N is the +number of LAMMPS atom types: + +filename +N element names = mapping of elements to atom types :ul + +See the "pair_coeff"_pair_coeff.html doc page for alternate ways +to specify the path for the potential file. + +As an example, imagine a file SiC.nb3bharmonic has potential values +for Si and C. If your LAMMPS simulation has 4 atoms types and you +want the 1st 3 to be Si, and the 4th to be C, you would use the +following pair_coeff command: + +pair_coeff * * SiC.nb3bharmonic Si Si Si C :pre + +The 1st 2 arguments must be * * so as to span all LAMMPS atom types. +The first three Si arguments map LAMMPS atom types 1,2,3 to the Si +element in the potential file. The final C argument maps LAMMPS atom +type 4 to the C element in the potential file. If a mapping value is +specified as NULL, the mapping is not performed. This can be used +when the potential is used as part of the {hybrid} pair style. The +NULL values are placeholders for atom types that will be used with +other potentials. An example of a pair_coeff command for use with the +{hybrid} pair style is: + +pair_coeff * * 3bnbharm MgOH.3bnbharm Mg O H + +Three-body nonbonded harmonic files in the {potentials} directory of +the LAMMPS distribution have a ".nb3bharmonic" suffix. Lines that are +not blank or comments (starting with #) define parameters for a +triplet of elements. + +Each entry has six arguments. The first three are atom types as +referenced in the LAMMPS input file. The first argument specifies the +central atom. The fourth argument indicates the {K} parameter. The +fifth argument indicates {theta_0}. The sixth argument indicates a +separation cutoff in Angstroms. + +For a given entry, if the second and third arguments are identical, +then the entry is for a cutoff for the distance between types 1 and 2 +(values for {K} and {theta_0} are irrelevant in this case). + +For a given entry, if the first three arguments are all different, +then the entry is for the {K} and {theta_0} parameters (the cutoff in +this case is irrelevant). + +It is {not} required that the potential file contain entries for all +of the elements listed in the pair_coeff command. It can also contain +entries for additional elements not being used in a particular +simulation; LAMMPS ignores those entries. + +:line + +[Restrictions:] + +This pair style can only be used if LAMMPS was built with the +USER_MISC package. See the "Making LAMMPS"_Section_start.html#start_3 +section for more info on packages. + +[Related commands:] + +"pair_coeff"_pair_coeff.html + +[Default:] none