36 lines
1.7 KiB
ReStructuredText
36 lines
1.7 KiB
ReStructuredText
Calculate temperature
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=====================
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Temperature is computed as kinetic energy divided by some number of
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degrees of freedom (and the Boltzmann constant). Since kinetic energy
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is a function of particle velocity, there is often a need to
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distinguish between a particle's advection velocity (due to some
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aggregate motion of particles) and its thermal velocity. The sum of
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the two is the particle's total velocity, but the latter is often what
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is wanted to compute a temperature.
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LAMMPS has several options for computing temperatures, any of which
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can be used in :doc:`thermostatting <Howto_thermostat>` and
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:doc:`barostatting <Howto_barostat>`. These :doc:`compute commands <compute>` calculate temperature:
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* :doc:`compute temp <compute_temp>`
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* :doc:`compute temp/sphere <compute_temp_sphere>`
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* :doc:`compute temp/asphere <compute_temp_asphere>`
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* :doc:`compute temp/com <compute_temp_com>`
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* :doc:`compute temp/deform <compute_temp_deform>`
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* :doc:`compute temp/partial <compute_temp_partial>`
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* :doc:`compute temp/profile <compute_temp_profile>`
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* :doc:`compute temp/ramp <compute_temp_ramp>`
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* :doc:`compute temp/region <compute_temp_region>`
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All but the first 3 calculate velocity biases directly (e.g. advection
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velocities) that are removed when computing the thermal temperature.
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:doc:`Compute temp/sphere <compute_temp_sphere>` and :doc:`compute temp/asphere <compute_temp_asphere>` compute kinetic energy for
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finite-size particles that includes rotational degrees of freedom.
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They both allow for velocity biases indirectly, via an optional extra
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argument which is another temperature compute that subtracts a
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velocity bias. This allows the translational velocity of spherical or
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aspherical particles to be adjusted in prescribed ways.
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