From 35a5e6fdc18f3de28d2900476663129ad20c35ec Mon Sep 17 00:00:00 2001 From: sjplimp Date: Fri, 26 Oct 2012 23:28:14 +0000 Subject: [PATCH] git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@9023 f3b2605a-c512-4ea7-a41b-209d697bcdaa --- doc/pair_meam_sw_spline.html | 137 +++++++++++++++++++++++++++++++++++ doc/pair_meam_sw_spline.txt | 130 +++++++++++++++++++++++++++++++++ 2 files changed, 267 insertions(+) create mode 100644 doc/pair_meam_sw_spline.html create mode 100644 doc/pair_meam_sw_spline.txt diff --git a/doc/pair_meam_sw_spline.html b/doc/pair_meam_sw_spline.html new file mode 100644 index 0000000000..cbe4c18ba5 --- /dev/null +++ b/doc/pair_meam_sw_spline.html @@ -0,0 +1,137 @@ + +
LAMMPS WWW Site - LAMMPS Documentation - LAMMPS Commands +
+ + + + + + +
+ +

pair_style meam/sw/spline +

+

pair_style meam/sw/spline/omp +

+

Syntax: +

+
pair_style meam/sw/spline 
+
+

Examples: +

+
pair_style meam/sw/spline
+pair_coeff * * Ti.meam.sw.spline Ti
+pair_coeff * * Ti.meam.sw.spline Ti Ti Ti 
+
+

Description: +

+

The meam/sw/spline style computes pairwise interactions for metals +using a variant of modified embedded-atom method (MEAM) +potentials (Lenosky) with an additional Stillinger-Weber (SW) +term (Stillinger) in the energy. This form of the +potential was first proposed +by Nicklas, Fellinger, and Park (Nicklas). +We refer to it as MEAM+SW. The total energy E is given by +

+
+
+

where rho_I is the density at atom I, theta_JIK is the angle between +atoms J, I, and K centered on atom I. The seven functions +Phi, F, G, U, rho, f, and g are represented by cubic splines. +

+

The cutoffs and the coefficients for these spline functions are listed +in a parameter file which is specified by the pair_coeff +command. Parameter files for different elements are +included in the "potentials" directory of the LAMMPS distribution and +have a ".meam.sw.spline" file suffix. +All of these files are parameterized in terms of +LAMMPS metal units. +

+

Note that unlike for other potentials, cutoffs for spline-based +MEAM+SW potentials are not set in the pair_style or pair_coeff +command; they are specified in the potential files themselves. +

+

Unlike the EAM pair style, which retrieves the atomic mass from +the potential file, the spline-based MEAM+SW potentials do not include +mass information; thus you need to use the mass +command to specify it. +

+

Only a single pair_coeff command is used with the meam/sw/spline style +which specifies a potential file with parameters for all needed 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: +

+ +

As an example, imagine the Ti.meam.sw.spline file has values for Ti. +If your LAMMPS simulation has 3 atoms types and they are all to be +treated with this potential, you would use the following pair_coeff command: +

+

pair_coeff * * Ti.meam.sw.spline Ti Ti Ti +

+

The 1st 2 arguments must be * * so as to span all LAMMPS atom types. +The three Ti arguments map LAMMPS atom types 1,2,3 to the Ti element +in the potential file. If a mapping value is specified as NULL, the +mapping is not performed. This can be used when a meam/sw/spline +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. +

+

IMPORTANT NOTE: The meam/sw/spline style currently supports only +single-element MEAM+SW potentials. It may be extended for alloy systems +in the future. +

+
+ +

Mixing, shift, table, tail correction, restart, rRESPA info: +

+

The pair style does not support multiple element types or mixing. +It has been designed for pure elements only. +

+

This pair style does not support the pair_modify +shift, table, and tail options. +

+

The meam/sw/spline pair style does not write its information to +binary restart files, since it is stored in an external +potential parameter file. Thus, you need to re-specify the pair_style +and pair_coeff commands in an input script that reads a restart file. +

+

The meam/sw/spline pair style can only be used via the pair keyword of the +run_style respa command. They do not support the +inner, middle, outer keywords. +

+
+ +

Restrictions: +

+

This pair style requires the newton setting to be "on" +for pair interactions. +

+

This pair style is only enabled if LAMMPS was built with the USER-MISC package. +See the Making LAMMPS section for more info. +

+

Related commands: +

+

pair_coeff pair_style meam pair_style meam/spline +

+

Default: none +

+
+ + + +

(Lenosky) Lenosky, Sadigh, Alonso, Bulatov, de la Rubia, Kim, Voter, Kress, Modell. Simul. Mater. Sci. Eng. 8, 825 (2000). +

+ + +

(Stillinger) Stillinger, Weber, Phys. Rev. B 31, 5262 (1985). +

+ + +

(Nicklas) +The spline-based MEAM+SW format was first devised and used to develop +potentials for bcc transition metals by Jeremy Nicklas, Michael Fellinger, +and Hyoungki Park at The Ohio State University. +

+ diff --git a/doc/pair_meam_sw_spline.txt b/doc/pair_meam_sw_spline.txt new file mode 100644 index 0000000000..0098e24a76 --- /dev/null +++ b/doc/pair_meam_sw_spline.txt @@ -0,0 +1,130 @@ +"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 meam/sw/spline :h3 +pair_style meam/sw/spline/omp :h3 + +[Syntax:] + +pair_style meam/sw/spline :pre + +[Examples:] + +pair_style meam/sw/spline +pair_coeff * * Ti.meam.sw.spline Ti +pair_coeff * * Ti.meam.sw.spline Ti Ti Ti :pre + +[Description:] + +The {meam/sw/spline} style computes pairwise interactions for metals +using a variant of modified embedded-atom method (MEAM) +potentials "(Lenosky)"_#Lenosky with an additional Stillinger-Weber (SW) +term "(Stillinger)"_#Stillinger in the energy. This form of the +potential was first proposed +by Nicklas, Fellinger, and Park "(Nicklas)"_#Nicklas. +We refer to it as MEAM+SW. The total energy E is given by + +:c,image(pair_meam_sw_spline.jpg) + +where rho_I is the density at atom I, theta_JIK is the angle between +atoms J, I, and K centered on atom I. The seven functions +Phi, F, G, U, rho, f, and g are represented by cubic splines. + +The cutoffs and the coefficients for these spline functions are listed +in a parameter file which is specified by the "pair_coeff"_pair_coeff.html +command. Parameter files for different elements are +included in the "potentials" directory of the LAMMPS distribution and +have a ".meam.sw.spline" file suffix. +All of these files are parameterized in terms of +LAMMPS "metal units"_units.html. + +Note that unlike for other potentials, cutoffs for spline-based +MEAM+SW potentials are not set in the pair_style or pair_coeff +command; they are specified in the potential files themselves. + +Unlike the EAM pair style, which retrieves the atomic mass from +the potential file, the spline-based MEAM+SW potentials do not include +mass information; thus you need to use the "mass"_mass.html +command to specify it. + +Only a single pair_coeff command is used with the meam/sw/spline style +which specifies a potential file with parameters for all needed 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 spline-based MEAM+SW elements to atom types :ul + +As an example, imagine the Ti.meam.sw.spline file has values for Ti. +If your LAMMPS simulation has 3 atoms types and they are all to be +treated with this potential, you would use the following pair_coeff command: + +pair_coeff * * Ti.meam.sw.spline Ti Ti Ti + +The 1st 2 arguments must be * * so as to span all LAMMPS atom types. +The three Ti arguments map LAMMPS atom types 1,2,3 to the Ti element +in the potential file. If a mapping value is specified as NULL, the +mapping is not performed. This can be used when a {meam/sw/spline} +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. + +IMPORTANT NOTE: The {meam/sw/spline} style currently supports only +single-element MEAM+SW potentials. It may be extended for alloy systems +in the future. + +:line + +[Mixing, shift, table, tail correction, restart, rRESPA info]: + +The pair style does not support multiple element types or mixing. +It has been designed for pure elements only. + +This pair style does not support the "pair_modify"_pair_modify.html +shift, table, and tail options. + +The {meam/sw/spline} pair style does not write its information to +"binary restart files"_restart.html, since it is stored in an external +potential parameter file. Thus, you need to re-specify the pair_style +and pair_coeff commands in an input script that reads a restart file. + +The {meam/sw/spline} pair style can only be used via the {pair} keyword of the +"run_style respa"_run_style.html command. They do not support the +{inner}, {middle}, {outer} keywords. + +:line + +[Restrictions:] + +This pair style requires the "newton"_newton.html setting to be "on" +for pair interactions. + +This pair style is only enabled if LAMMPS was built with the USER-MISC package. +See the "Making LAMMPS"_Section_start.html#start_3 section for more info. + +[Related commands:] + +"pair_coeff"_pair_coeff.html "pair_style meam"_pair_meam.html "pair_style meam/spline"_pair_meam_spline.html + +[Default:] none + +:line + +:link(Lenosky) +[(Lenosky)] Lenosky, Sadigh, Alonso, Bulatov, de la Rubia, Kim, Voter, Kress, Modell. Simul. Mater. Sci. Eng. 8, 825 (2000). + +:link(Stillinger) +[(Stillinger)] Stillinger, Weber, Phys. Rev. B 31, 5262 (1985). + +:link(Nicklas) +[(Nicklas)] +The spline-based MEAM+SW format was first devised and used to develop +potentials for bcc transition metals by Jeremy Nicklas, Michael Fellinger, +and Hyoungki Park at The Ohio State University. + +