forked from lijiext/lammps
112 lines
4.1 KiB
Plaintext
112 lines
4.1 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 property/atom command :h3
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[Syntax:]
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compute ID group-ID property/atom input1 input2 ... :pre
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ID, group-ID are documented in "compute"_compute.html command :ulb,l
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property/atom = style name of this compute command :l
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input = one or more atom attributes :l
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possible attributes = id, mol, type, mass,
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x, y, z, xs, ys, zs, xu, yu, zu, ix, iy, iz,
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vx, vy, vz, fx, fy, fz,
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q, mux, muy, muz, mu,
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radius, diameter, omegax, omegay, omegaz,
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angmomx, angmomy, angmomz,
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shapex,shapey, shapez,
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quatw, quati, quatj, quatk, tqx, tqy, tqz,
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spin, eradius, ervel, erforce :pre
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id = atom ID
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mol = molecule ID
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type = atom type
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mass = atom mass
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x,y,z = unscaled atom coordinates
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xs,ys,zs = scaled atom coordinates
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xu,yu,zu = unwrapped atom coordinates
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ix,iy,iz = box image that the atom is in
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vx,vy,vz = atom velocities
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fx,fy,fz = forces on atoms
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q = atom charge
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mux,muy,muz = orientation of dipole moment of atom
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mu = magnitude of dipole moment of atom
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radius,diameter = radius,diameter of spherical particle
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omegax,omegay,omegaz = angular velocity of extended particle
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angmomx,angmomy,angmomz = angular momentum of extended particle
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tqx,tqy,tqz = torque on extended particles
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spin = electron spin
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eradius = electron radius
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ervel = electron radial velocity
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erforce = electron radial force
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shapex,shapey,shapez = 3 diameters of aspherical particle
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quatw,quati,quatj,quatk = quaternion components for aspherical particles :pre
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:ule
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[Examples:]
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compute 1 all property/atom xs vx fx mux
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compute 2 all property/atom type
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compute 1 all property/atom ix iy iz :pre
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[Description:]
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Define a computation that simply stores atom attributes for each atom
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in the group. This is useful so that the values can be used by other
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"output commands"_Section_howto.html#4_15 that take computes as
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inputs. See for example, the "compute reduce"_compute_reduce.html,
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"fix ave/atom"_fix_ave_atom.html, "fix ave/histo"_fix_ave_histo.html,
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"fix ave/spatial"_fix_ave_spatial.html, and "atom-style
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variable"_variable.html commands.
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The list of possible attributes is the same as that used by the "dump
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custom"_dump.html command, which describes their meaning, with some
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additional quantities that are only defined for certain "atom
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styles"_atom_style.html. Basically, this list gives your input script
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access to any per-atom quantity stored by LAMMPS.
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The values are stored in a per-atom vector or array as
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discussed below. Zeroes are stored for atoms not in the specified
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group.
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The additional quantities only accessible via this command (and not
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directly via the "dump custom"_dump.html command are as follows.
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{Shapex}, {shapey}, and {shapez} are defined for ellipsoidal particles
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and define the 3d shape of each particle. {Quatw}, {quati}, {quatj},
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and {quatk} are also defined for ellipsoidal particles and store the
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4-vector quaternion representing the orientation of each particle.
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See the "set"_set.html command for an explanation of the quaternion
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vector.
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[Output info:]
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This compute calculates a per-atom vector or per-atom array depending
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on the number of input values. If a single input is specified, a
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per-atom vector is produced. If two or more inputs are specified, a
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per-atom array is produced where the number of columns = the number of
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inputs. The vector or array can be accessed by any command that uses
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per-atom values from a compute as input. See "this
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section"_Section_howto.html#4_15 for an overview of LAMMPS output
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options.
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The vector or array values will be in whatever "units"_units.html the
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corresponding attribute is in, e.g. velocity units for vx, charge
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units for q, etc.
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[Restrictions:] none
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[Related commands:]
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"dump custom"_dump.html, "compute reduce"_compute_reduce.html, "fix
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ave/atom"_fix_ave_atom.html, "fix ave/spatial"_fix_ave_spatial.html
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[Default:] none
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