forked from lijiext/lammps
63 lines
1.8 KiB
Plaintext
63 lines
1.8 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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newton command :h3
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[Syntax:]
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newton flag
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newton flag1 flag2 :pre
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flag = {on} or {off} for both pairwise and bonded interactions
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flag1 = {on} or {off} for pairwise interactions
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flag2 = {on} or {off} for bonded interactions :ul
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[Examples:]
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newton off
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newton on off :pre
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[Description:]
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This command turns Newton's 3rd law {on} or {off} for pairwise and
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bonded interactions. For most problems, setting Newton's 3rd law to
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{on} means a modest savings in computation at the cost of two times
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more communication. Whether this is faster depends on problem size,
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force cutoff lengths, a machine's compute/communication ratio, and how
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many processors are being used.
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Setting the pairwise newton flag to {off} means that if two
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interacting atoms are on different processors, both processors compute
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their interaction and the resulting force information is not
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communicated. Similarly, for bonded interactions, newton {off} means
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that if a bond, angle, dihedral, or improper interaction contains
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atoms on 2 or more processors, the interaction is computed by each
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processor.
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LAMMPS should produce the same answers for any newton flag settings,
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except for round-off issues.
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With "run_style"_run_style.html {respa} and only bonded interactions
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(bond, angle, etc) computed in the innermost timestep, it may be
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faster to turn newton {off} for bonded interactions, to avoid extra
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communication in the innermost loop.
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[Restrictions:]
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The newton bond setting cannot be changed after the simulation box is
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defined by a "read_data"_read_data.html or
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"create_box"_create_box.html command.
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[Related commands:]
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"run_style"_run_style.html respa
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[Default:]
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newton on :pre
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