Page Menu
Home
c4science
Search
Configure Global Search
Log In
Files
F90780674
compute_property_atom.html
No One
Temporary
Actions
Download File
Edit File
Delete File
View Transforms
Subscribe
Mute Notifications
Award Token
Subscribers
None
File Metadata
Details
File Info
Storage
Attached
Created
Mon, Nov 4, 16:55
Size
7 KB
Mime Type
text/html
Expires
Wed, Nov 6, 16:55 (2 d)
Engine
blob
Format
Raw Data
Handle
22133628
Attached To
rLAMMPS lammps
compute_property_atom.html
View Options
<HTML>
<CENTER><A HREF = "http://lammps.sandia.gov">LAMMPS WWW Site</A> - <A HREF = "Manual.html">LAMMPS Documentation</A> - <A HREF = "Section_commands.html#comm">LAMMPS Commands</A>
</CENTER>
<HR>
<H3>compute property/atom command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>compute ID group-ID property/atom input1 input2 ...
</PRE>
<UL><LI>ID, group-ID are documented in <A HREF = "compute.html">compute</A> command
<LI>property/atom = style name of this compute command
<LI>input = one or more atom attributes
<PRE> possible attributes = id, mol, proc, type, mass,
x, y, z, xs, ys, zs, xu, yu, zu, ix, iy, iz,
vx, vy, vz, fx, fy, fz,
q, mux, muy, muz, mu,
radius, diameter, omegax, omegay, omegaz,
angmomx, angmomy, angmomz,
shapex,shapey, shapez,
quatw, quati, quatj, quatk, tqx, tqy, tqz,
end1x, end1y, end1z, end2x, end2y, end2z,
corner1x, corner1y, corner1z,
corner2x, corner2y, corner2z,
corner3x, corner3y, corner3z,
nbonds,
vfrac, s0,
spin, eradius, ervel, erforce,
rho, drho, e, de, cv,
i_name, d_name
</PRE>
<PRE> id = atom ID
mol = molecule ID
proc = ID of processor that owns atom
type = atom type
mass = atom mass
x,y,z = unscaled atom coordinates
xs,ys,zs = scaled atom coordinates
xu,yu,zu = unwrapped atom coordinates
ix,iy,iz = box image that the atom is in
vx,vy,vz = atom velocities
fx,fy,fz = forces on atoms
q = atom charge
mux,muy,muz = orientation of dipole moment of atom
mu = magnitude of dipole moment of atom
radius,diameter = radius,diameter of spherical particle
omegax,omegay,omegaz = angular velocity of spherical particle
angmomx,angmomy,angmomz = angular momentum of aspherical particle
shapex,shapey,shapez = 3 diameters of aspherical particle
quatw,quati,quatj,quatk = quaternion components for aspherical or body particles
tqx,tqy,tqz = torque on finite-size particles
end12x, end12y, end12z = end points of line segment
corner123x, corner123y, corner123z = corner points of triangle
nbonds = number of bonds assigned to an atom
</PRE>
<PRE> PERI package per-atom properties:
vfrac = ???
s0 = ???
</PRE>
<PRE> USER-EFF and USER-AWPMD package per-atom properties:
spin = electron spin
eradius = electron radius
ervel = electron radial velocity
erforce = electron radial force
</PRE>
<PRE> USER-SPH package per-atom properties:
rho = ???
drho = ???
e = ???
de = ???
cv = ???
</PRE>
<PRE> <A HREF = "fix_property_atom.html">fix property/atom</A> per-atom properties:
i_name = custom integer vector with name
d_name = custom integer vector with name
</PRE>
</UL>
<P><B>Examples:</B>
</P>
<PRE>compute 1 all property/atom xs vx fx mux
compute 2 all property/atom type
compute 1 all property/atom ix iy iz
</PRE>
<P><B>Description:</B>
</P>
<P>Define a computation that simply stores atom attributes for each atom
in the group. This is useful so that the values can be used by other
<A HREF = "Section_howto.html#howto_15">output commands</A> that take computes as
inputs. See for example, the <A HREF = "compute_reduce.html">compute reduce</A>,
<A HREF = "fix_ave_atom.html">fix ave/atom</A>, <A HREF = "fix_ave_histo.html">fix ave/histo</A>,
<A HREF = "fix_ave_spatial.html">fix ave/spatial</A>, and <A HREF = "variable.html">atom-style
variable</A> commands.
</P>
<P>The list of possible attributes is the same as that used by the <A HREF = "dump.html">dump
custom</A> command, which describes their meaning, with some
additional quantities that are only defined for certain <A HREF = "atom_style.html">atom
styles</A>. Basically, this augmented list gives an
input script access to any per-atom quantity stored by LAMMPS.
</P>
<P>The values are stored in a per-atom vector or array as discussed
below. Zeroes are stored for atoms not in the specified group or for
quantities that are not defined for a particular particle in the group
(e.g. <I>shapex</I> if the particle is not an ellipsoid).
</P>
<P>The additional quantities only accessible via this command, and not
directly via the <A HREF = "dump.html">dump custom</A> command, are as follows.
</P>
<P><I>Shapex</I>, <I>shapey</I>, and <I>shapez</I> are defined for ellipsoidal particles
and define the 3d shape of each particle.
</P>
<P><I>Quatw</I>, <I>quati</I>, <I>quatj</I>, and <I>quatk</I> are defined for ellipsoidal
particles and body particles and store the 4-vector quaternion
representing the orientation of each particle. See the <A HREF = "set.html">set</A>
command for an explanation of the quaternion vector.
</P>
<P><I>End1x</I>, <I>end1y</I>, <I>end1z</I>, <I>end2x</I>, <I>end2y</I>, <I>end2z</I>, are defined for
line segment particles and define the end points of each line segment.
</P>
<P><I>Corner1x</I>, <I>corner1y</I>, <I>corner1z</I>, <I>corner2x</I>, <I>corner2y</I>,
<I>corner2z</I>, <I>corner3x</I>, <I>corner3y</I>, <I>corner3z</I>, are defined for
triangular particles and define the corner points of each triangle.
</P>
<P><I>Nbonds</I> is available for all molecular atom styles and refers to the
number of explicit bonds assigned to an atom. Note that if the
<A HREF = "newton.html">newton bond</A> command is set to <I>on</I>, which is the
default, then every bond in the system is assigned to only one of the
two atoms in the bond. Thus a bond between atoms I,J may be tallied
for either atom I or atom J. If <A HREF = "newton.html">newton bond off</A> is set,
it will be tallied with both atom I and atom J.
</P>
<P>The <I>i_name</I> and <I>d_name</I> attributes refer to custom integer and
floating-point properties that have been added to each atom via the
<A HREF = "fix_property_atom.html">fix property/atom</A> command. When that command
is used specific names are given to each attribute which are what is
specified as the "name" portion of <I>i_name</I> or <I>d_name</I>.
</P>
<P><B>Output info:</B>
</P>
<P>This compute calculates a per-atom vector or per-atom array depending
on the number of input values. If a single input is specified, a
per-atom vector is produced. If two or more inputs are specified, a
per-atom array is produced where the number of columns = the number of
inputs. The vector or array can be accessed by any command that uses
per-atom values from a compute as input. See <A HREF = "Section_howto.html#howto_15">this
section</A> for an overview of LAMMPS output
options.
</P>
<P>The vector or array values will be in whatever <A HREF = "units.html">units</A> the
corresponding attribute is in, e.g. velocity units for vx, charge
units for q, etc.
</P>
<P><B>Restrictions:</B> none
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "dump.html">dump custom</A>, <A HREF = "compute_reduce.html">compute reduce</A>, <A HREF = "fix_ave_atom.html">fix
ave/atom</A>, <A HREF = "fix_ave_spatial.html">fix ave/spatial</A>,
<A HREF = "fix_property_atom.html">fix property/atom</A>
</P>
<P><B>Default:</B> none
</P>
</HTML>
Event Timeline
Log In to Comment