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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 >
< li class = "toctree-l1" > < a class = "reference internal" href = "Section_commands.html" > 3. Commands< / a > < / li >
< li class = "toctree-l1" > < a class = "reference internal" href = "Section_packages.html" > 4. Packages< / a > < / li >
< li class = "toctree-l1" > < a class = "reference internal" href = "Section_accelerate.html" > 5. Accelerating LAMMPS performance< / a > < / li >
< li class = "toctree-l1" > < a class = "reference internal" href = "Section_howto.html" > 6. How-to discussions< / 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 >
< li class = "toctree-l1" > < a class = "reference internal" href = "Section_python.html" > 11. Python interface to LAMMPS< / a > < / li >
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< li > compute temp command< / li >
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< a href = "http://lammps.sandia.gov" > Website< / a >
< a href = "Section_commands.html#comm" > Commands< / a >
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< div class = "section" id = "compute-temp-command" >
< span id = "index-0" > < / span > < h1 > compute temp command< / h1 >
< / div >
< div class = "section" id = "compute-temp-kk-command" >
< h1 > compute temp/kk command< / h1 >
< div class = "section" id = "syntax" >
< h2 > Syntax< / h2 >
< div class = "highlight-default" > < div class = "highlight" > < pre > < span > < / span > < span class = "n" > compute< / span > < span class = "n" > ID< / span > < span class = "n" > group< / span > < span class = "o" > -< / span > < span class = "n" > ID< / span > < span class = "n" > temp< / span >
< / pre > < / div >
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< ul class = "simple" >
< li > ID, group-ID are documented in < a class = "reference internal" href = "compute.html" > < span class = "doc" > compute< / span > < / a > command< / li >
< li > temp = style name of this compute command< / li >
< / ul >
< / div >
< div class = "section" id = "examples" >
< h2 > Examples< / h2 >
< div class = "highlight-default" > < div class = "highlight" > < pre > < span > < / span > < span class = "n" > compute< / span > < span class = "mi" > 1< / span > < span class = "nb" > all< / span > < span class = "n" > temp< / span >
< span class = "n" > compute< / span > < span class = "n" > myTemp< / span > < span class = "n" > mobile< / span > < span class = "n" > temp< / span >
< / pre > < / div >
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< div class = "section" id = "description" >
< h2 > Description< / h2 >
< p > Define a computation that calculates the temperature of a group of
atoms. A compute of this style can be used by any command that
computes a temperature, e.g. < a class = "reference internal" href = "thermo_modify.html" > < span class = "doc" > thermo_modify< / span > < / a > , < a class = "reference internal" href = "fix_temp_rescale.html" > < span class = "doc" > fix temp/rescale< / span > < / a > , < a class = "reference internal" href = "fix_nh.html" > < span class = "doc" > fix npt< / span > < / a > , etc.< / p >
< p > The temperature is calculated by the formula KE = dim/2 N k T, where
KE = total kinetic energy of the group of atoms (sum of 1/2 m v^2),
dim = 2 or 3 = dimensionality of the simulation, N = number of atoms
in the group, k = Boltzmann constant, and T = temperature.< / p >
< p > A kinetic energy tensor, stored as a 6-element vector, is also
calculated by this compute for use in the computation of a pressure
tensor. The formula for the components of the tensor is the same as
the above formula, except that v^2 is replaced by vx*vy for the xy
component, etc. The 6 components of the vector are ordered xx, yy,
zz, xy, xz, yz.< / p >
< p > The number of atoms contributing to the temperature is assumed to be
constant for the duration of the run; use the < em > dynamic< / em > option of the
< a class = "reference internal" href = "compute_modify.html" > < span class = "doc" > compute_modify< / span > < / a > command if this is not the case.< / p >
< p > This compute subtracts out degrees-of-freedom due to fixes that
constrain molecular motion, such as < a class = "reference internal" href = "fix_shake.html" > < span class = "doc" > fix shake< / span > < / a > and
< a class = "reference internal" href = "fix_rigid.html" > < span class = "doc" > fix rigid< / span > < / a > . This means the temperature of groups of
atoms that include these constraints will be computed correctly. If
needed, the subtracted degrees-of-freedom can be altered using the
< em > extra< / em > option of the < a class = "reference internal" href = "compute_modify.html" > < span class = "doc" > compute_modify< / span > < / a > command.< / p >
< p > A compute of this style with the ID of “ thermo_temp” is created when
LAMMPS starts up, as if this command were in the input script:< / p >
< div class = "highlight-default" > < div class = "highlight" > < pre > < span > < / span > < span class = "n" > compute< / span > < span class = "n" > thermo_temp< / span > < span class = "nb" > all< / span > < span class = "n" > temp< / span >
< / pre > < / div >
< / div >
< p > See the “ thermo_style” command for more details.< / p >
< p > See < a class = "reference internal" href = "Section_howto.html#howto-16" > < span class = "std std-ref" > this howto section< / span > < / a > of the manual for
a discussion of different ways to compute temperature and perform
thermostatting.< / p >
< hr class = "docutils" / >
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< p > Styles with a < 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
hardware, as discussed in < a class = "reference internal" href = "Section_accelerate.html" > < span class = "doc" > Section_accelerate< / span > < / a >
of the manual. The accelerated styles take the same arguments and
should produce the same results, except for round-off and precision
issues.< / p >
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< p > These accelerated styles are part of the GPU, USER-INTEL, KOKKOS,
USER-OMP and OPT packages, respectively. They are only enabled if
LAMMPS was built with those packages. See the < a class = "reference internal" href = "Section_start.html#start-3" > < span class = "std std-ref" > Making LAMMPS< / span > < / a > section for more info.< / p >
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< 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 class = "std std-ref" > -suffix command-line switch< / span > < / a > when you invoke LAMMPS, or you can
use the < a class = "reference internal" href = "suffix.html" > < span class = "doc" > suffix< / span > < / a > command in your input script.< / p >
< p > See < a class = "reference internal" href = "Section_accelerate.html" > < span class = "doc" > Section_accelerate< / span > < / a > of the manual for
more instructions on how to use the accelerated styles effectively.< / p >
< hr class = "docutils" / >
< p > < strong > Output info:< / strong > < / p >
< p > This compute calculates a global scalar (the temperature) and a global
vector of length 6 (KE tensor), which can be accessed by indices 1-6.
These values can be used by any command that uses global scalar or
vector values from a compute as input. See < a class = "reference internal" href = "Section_howto.html#howto-15" > < span class = "std std-ref" > this section< / span > < / a > for an overview of LAMMPS output
options.< / p >
< p > The scalar value calculated by this compute is “ intensive” . The
vector values are “ extensive” .< / p >
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< p > The scalar value will be in temperature < a class = "reference internal" href = "units.html" > < span class = "doc" > units< / span > < / a > . The
vector values will be in energy < a class = "reference internal" href = "units.html" > < span class = "doc" > units< / span > < / a > .< / p >
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< / div >
< div class = "section" id = "restrictions" >
< h2 > Restrictions< / h2 >
< blockquote >
< div > none< / div > < / blockquote >
< / div >
< div class = "section" id = "related-commands" >
< h2 > Related commands< / h2 >
< p > < a class = "reference internal" href = "compute_temp_partial.html" > < span class = "doc" > compute temp/partial< / span > < / a > , < a class = "reference internal" href = "compute_temp_region.html" > < span class = "doc" > compute temp/region< / span > < / a > , < a class = "reference internal" href = "compute_pressure.html" > < span class = "doc" > compute pressure< / span > < / a > < / p >
< p > < strong > Default:< / strong > none< / p >
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