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< title > pair_style meam/spline — LAMMPS 15 May 2015 version documentation< / title >
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2012-02-02 06:44:58 +08:00
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2012-02-02 06:44:58 +08:00
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2012-02-02 06:44:58 +08:00
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2012-02-02 06:44:58 +08:00
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< li class = "toctree-l1" > < a class = "reference internal" href = "Section_intro.html" > 1. Introduction< / a > < / li >
< li class = "toctree-l1" > < a class = "reference internal" href = "Section_start.html" > 2. Getting Started< / a > < / li >
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< li class = "toctree-l1" > < a class = "reference internal" href = "Section_perf.html" > 8. Performance & scalability< / a > < / li >
< li class = "toctree-l1" > < a class = "reference internal" href = "Section_tools.html" > 9. Additional tools< / a > < / li >
< li class = "toctree-l1" > < a class = "reference internal" href = "Section_modify.html" > 10. Modifying & extending LAMMPS< / a > < / li >
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< li > pair_style meam/spline< / li >
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< h1 > pair_style meam/spline< a class = "headerlink" href = "#pair-style-meam-spline" title = "Permalink to this headline" > ¶< / a > < / h1 >
< / div >
< div class = "section" id = "pair-style-meam-spline-omp" >
< h1 > pair_style meam/spline/omp< a class = "headerlink" href = "#pair-style-meam-spline-omp" title = "Permalink to this headline" > ¶< / a > < / h1 >
< div class = "section" id = "syntax" >
< h2 > Syntax< a class = "headerlink" href = "#syntax" title = "Permalink to this headline" > ¶< / a > < / h2 >
< div class = "highlight-python" > < div class = "highlight" > < pre > pair_style meam/spline
< / pre > < / div >
< / div >
< / div >
< div class = "section" id = "examples" >
< h2 > Examples< a class = "headerlink" href = "#examples" title = "Permalink to this headline" > ¶< / a > < / h2 >
< div class = "highlight-python" > < div class = "highlight" > < pre > pair_style meam/spline
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pair_coeff * * Ti.meam.spline Ti
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pair_coeff * * Ti.meam.spline Ti Ti Ti
< / pre > < / div >
< / div >
< / div >
< div class = "section" id = "description" >
< h2 > Description< a class = "headerlink" href = "#description" title = "Permalink to this headline" > ¶< / a > < / h2 >
< p > The < em > meam/spline< / em > style computes pairwise interactions for metals
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using a variant of modified embedded-atom method (MEAM) potentials
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< a class = "reference internal" href = "pair_meam_sw_spline.html#lenosky" > < span > (Lenosky)< / span > < / a > . The total energy E is given by< / p >
< img alt = "_images/pair_meam_spline.jpg" class = "align-center" src = "_images/pair_meam_spline.jpg" / >
< p > where rho_i is the density at atom I, theta_jik is the angle between
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atoms J, I, and K centered on atom I. The five functions Phi, U, rho,
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f, and g are represented by cubic splines.< / p >
< p > The cutoffs and the coefficients for these spline functions are listed
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in a parameter file which is specified by the
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< a class = "reference internal" href = "pair_coeff.html" > < em > pair_coeff< / em > < / a > command. Parameter files for different
elements are included in the “ potentials” directory of the LAMMPS
distribution and have a ” .meam.spline” file suffix. All of these
files are parameterized in terms of LAMMPS < a class = "reference internal" href = "units.html" > < em > metal units< / em > < / a > .< / p >
< p > Note that unlike for other potentials, cutoffs for spline-based MEAM
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potentials are not set in the pair_style or pair_coeff command; they
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are specified in the potential files themselves.< / p >
< p > Unlike the EAM pair style, which retrieves the atomic mass from the
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potential file, the spline-based MEAM potentials do not include mass
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information; thus you need to use the < a class = "reference internal" href = "mass.html" > < em > mass< / em > < / a > command to
specify it.< / p >
< p > Only a single pair_coeff command is used with the < em > meam/spline< / em > style
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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,
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where N is the number of LAMMPS atom types:< / p >
< ul class = "simple" >
< li > filename< / li >
< li > N element names = mapping of spline-based MEAM elements to atom types< / li >
< / ul >
< p > See the < a class = "reference internal" href = "pair_coeff.html" > < em > pair_coeff< / em > < / a > doc page for alternate ways
to specify the path for the potential file.< / p >
< p > As an example, imagine the Ti.meam.spline file has values for Ti. If
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your LAMMPS simulation has 3 atoms types and they are all to be
treated with this potentials, you would use the following pair_coeff
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command:< / p >
< div class = "highlight-python" > < div class = "highlight" > < pre > pair_coeff * * Ti.meam.spline Ti Ti Ti
< / pre > < / div >
< / div >
< p > The 1st 2 arguments must be * * so as to span all LAMMPS atom types.
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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
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mapping is not performed. This can be used when a < em > meam/spline< / em >
potential is used as part of the < em > hybrid< / em > pair style. The NULL values
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are placeholders for atom types that will be used with other
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potentials.< / p >
< div class = "admonition warning" >
< p class = "first admonition-title" > Warning< / p >
< p class = "last" > The < em > meam/spline< / em > style currently supports only
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single-element MEAM potentials. It may be extended for alloy systems
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in the future.< / p >
< / div >
< hr class = "docutils" / >
< p > Styles with a < em > cuda< / em > , < em > gpu< / em > , < em > intel< / em > , < em > kk< / em > , < em > omp< / em > , or < em > opt< / em > suffix are
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functionally the same as the corresponding style without the suffix.
They have been optimized to run faster, depending on your available
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hardware, as discussed in < a class = "reference internal" href = "Section_accelerate.html" > < em > Section_accelerate< / em > < / a >
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of the manual. The accelerated styles take the same arguments and
should produce the same results, except for round-off and precision
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issues.< / p >
< p > These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL,
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KOKKOS, USER-OMP and OPT packages, respectively. They are only
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enabled if LAMMPS was built with those packages. See the < a class = "reference internal" href = "Section_start.html#start-3" > < span > Making LAMMPS< / span > < / a > section for more info.< / p >
< p > You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the < a class = "reference internal" href = "Section_start.html#start-7" > < span > -suffix command-line switch< / span > < / a > when you invoke LAMMPS, or you can
use the < a class = "reference internal" href = "suffix.html" > < em > suffix< / em > < / a > command in your input script.< / p >
< p > See < a class = "reference internal" href = "Section_accelerate.html" > < em > Section_accelerate< / em > < / a > of the manual for
more instructions on how to use the accelerated styles effectively.< / p >
< hr class = "docutils" / >
< p > < strong > Mixing, shift, table, tail correction, restart, rRESPA info< / strong > :< / p >
< p > The current version of this pair style does not support multiple
element types or mixing. It has been designed for pure elements only.< / p >
< p > This pair style does not support the < a class = "reference internal" href = "pair_modify.html" > < em > pair_modify< / em > < / a >
shift, table, and tail options.< / p >
< p > The < em > meam/spline< / em > pair style does not write its information to < a class = "reference internal" href = "restart.html" > < em > binary restart files< / em > < / a > , since it is stored in an external
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potential parameter file. Thus, you need to re-specify the pair_style
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and pair_coeff commands in an input script that reads a restart file.< / p >
< p > The < em > meam/spline< / em > pair style can only be used via the < em > pair< / em > keyword of the
< a class = "reference internal" href = "run_style.html" > < em > run_style respa< / em > < / a > command. They do not support the
< em > inner< / em > , < em > middle< / em > , < em > outer< / em > keywords.< / p >
< / div >
< hr class = "docutils" / >
< div class = "section" id = "restrictions" >
< h2 > Restrictions< a class = "headerlink" href = "#restrictions" title = "Permalink to this headline" > ¶< / a > < / h2 >
< p > This pair style requires the < a class = "reference internal" href = "newton.html" > < em > newton< / em > < / a > setting to be “ on”
for pair interactions.< / p >
< p > This pair style is only enabled if LAMMPS was built with the USER-MISC
package. See the < a class = "reference internal" href = "Section_start.html#start-3" > < span > Making LAMMPS< / span > < / a > section
for more info.< / p >
< / div >
< div class = "section" id = "related-commands" >
< h2 > Related commands< a class = "headerlink" href = "#related-commands" title = "Permalink to this headline" > ¶< / a > < / h2 >
< p > < a class = "reference internal" href = "pair_coeff.html" > < em > pair_coeff< / em > < / a > , < a class = "reference internal" href = "pair_meam.html" > < em > pair_style meam< / em > < / a > < / p >
< p > < strong > Default:< / strong > none< / p >
< hr class = "docutils" / >
< p id = "lenosky" > < strong > (Lenosky)< / strong > Lenosky, Sadigh, Alonso, Bulatov, de la Rubia, Kim, Voter,
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Kress, Modelling Simulation Materials Science Enginerring, 8, 825
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(2000).< / p >
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