forked from lijiext/lammps
78 lines
2.6 KiB
Plaintext
78 lines
2.6 KiB
Plaintext
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Section_commands.html#comm)
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:line
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compute ke/atom/eff command :h3
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[Syntax:]
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compute ID group-ID ke/atom/eff :pre
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ID, group-ID are documented in "compute"_compute.html command
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ke/atom/eff = style name of this compute command :ul
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[Examples:]
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compute 1 all ke/atom/eff :pre
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[Description:]
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Define a computation that calculates the per-atom translational
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(nuclei and electrons) and radial kinetic energy (electron only) in a
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group. The particles are assumed to be nuclei and electrons modeled
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with the "electronic force field"_pair_eff.html.
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The kinetic energy for each nucleus is computed as 1/2 m v^2, where m
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corresponds to the corresponding nuclear mass, and the kinetic energy
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for each electron is computed as 1/2 (me v^2 + 3/4 me s^2), where me
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and v correspond to the mass and translational velocity of each
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electron, and s to its radial velocity, respectively.
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There is a subtle difference between the quantity calculated by this
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compute and the kinetic energy calculated by the {ke} or {etotal}
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keyword used in thermodynamic output, as specified by the
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"thermo_style"_thermo_style.html command. For this compute, kinetic
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energy is "translational" plus electronic "radial" kinetic energy,
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calculated by the simple formula above. For thermodynamic output, the
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{ke} keyword infers kinetic energy from the temperature of the system
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with 1/2 Kb T of energy for each (nuclear-only) degree of freedom in
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eFF.
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IMPORTANT NOTE: The temperature in eFF should be monitored via the
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"compute temp/eff"_compute_temp_eff.html command, which can be printed
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with thermodynamic output by using the
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"thermo_modify"_thermo_modify.html command, as shown in the following
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example:
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compute effTemp all temp/eff
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thermo_style custom step etotal pe ke temp press
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thermo_modify temp effTemp :pre
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The value of the kinetic energy will be 0.0 for atoms (nuclei or
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electrons) not in the specified compute group.
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[Output info:]
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This compute calculates a scalar quantity for each atom, which can be
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accessed by any command that uses per-atom computes as input. See
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"Section_howto 15"_Section_howto.html#howto_15 for an overview of
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LAMMPS output options.
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The per-atom vector values will be in energy "units"_units.html.
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[Restrictions:]
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This compute is part of the USER-EFF package. It is only enabled if
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LAMMPS was built with that package. See the "Making
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LAMMPS"_Section_start.html#start_3 section for more info.
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[Related commands:]
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"dump custom"_dump.html
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[Default:] none
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