forked from lijiext/lammps
103 lines
4.1 KiB
Plaintext
103 lines
4.1 KiB
Plaintext
|
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
|
||
|
|
|
||
|
|
:link(lws,http://lammps.sandia.gov)
|
||
|
|
:link(ld,Manual.html)
|
||
|
|
:link(lc,Section_commands.html#comm)
|
||
|
|
|
||
|
|
:line
|
||
|
|
|
||
|
|
region command :h3
|
||
|
|
|
||
|
|
[Syntax:]
|
||
|
|
|
||
|
|
region ID style args keyword value ... :pre
|
||
|
|
|
||
|
|
ID = user-assigned name for the region :ulb,l
|
||
|
|
style = {block} or {sphere} or {cylinder} or {union} or {intersect} :l
|
||
|
|
{block} args = xlo xhi ylo yhi zlo zhi
|
||
|
|
xlo,xhi,ylo,yhi,zlo,zhi = bounds of block in all
|
||
|
|
dimensions (distance units)
|
||
|
|
{sphere} args = x y z radius
|
||
|
|
x,y,z = center of sphere (distance units)
|
||
|
|
radius = radius of sphere (distance units)
|
||
|
|
{cylinder} args = dim c1 c2 radius lo hi
|
||
|
|
dim = {x} or {y} or {z} = axis of cylinder
|
||
|
|
c1,c2 = coords of cylinder axis in other 2 dimensions (distance units)
|
||
|
|
radius = cylinder radius (distance units)
|
||
|
|
lo,hi = bounds of cylinder in dim (distance units)
|
||
|
|
{union} args = N reg-ID1 reg-ID2 ...
|
||
|
|
N = # of regions to follow, must be 2 or greater
|
||
|
|
reg-ID1,reg-ID2, ... = IDs of regions to join together
|
||
|
|
{intersect} args = N reg-ID1 reg-ID2 ...
|
||
|
|
N = # of regions to follow, must be 2 or greater
|
||
|
|
reg-ID1,reg-ID2, ... = IDs of regions to intersect :pre
|
||
|
|
zero or more keyword/value pairs may be appended to the args :l
|
||
|
|
keyword = {side} or {units} :l
|
||
|
|
{side} value = {in} or {out}
|
||
|
|
{in} = the region is inside the specified geometry
|
||
|
|
{out} = the region is outside the specified geometry
|
||
|
|
{units} value = {lattice} or {box}
|
||
|
|
{lattice} = the geometry is defined in lattice units
|
||
|
|
{box} = the geometry is defined in simulation box units :pre
|
||
|
|
:ule
|
||
|
|
|
||
|
|
[Examples:]
|
||
|
|
|
||
|
|
region 1 block -3.0 5.0 INF 10.0 INF INF
|
||
|
|
region 2 sphere 0.0 0.0 0.0 5 side out
|
||
|
|
region void cylinder y 2 3 5 -5.0 INF units box
|
||
|
|
region outside union 4 side1 side2 side3 side4 :pre
|
||
|
|
|
||
|
|
[Description:]
|
||
|
|
|
||
|
|
This command defines a geometric region of space. Various other
|
||
|
|
commands use regions. For example, the region can be filled with
|
||
|
|
atoms via the "create_atoms"_create_atoms.html command. Or the atoms
|
||
|
|
in the region can be identified as a group via the "group"_group.html
|
||
|
|
command, or deleted via the "delete_atoms"_delete_atoms.html command.
|
||
|
|
|
||
|
|
The lo/hi values for {block} or {cylinder} styles can be specified
|
||
|
|
as INF which means they extend all the way to the global simulation
|
||
|
|
box boundary. If a region is defined before the simulation box has
|
||
|
|
been created (via "create_box"_create_box.html or
|
||
|
|
"read_data"_read_data.html or "read_restart"_read_restart.html
|
||
|
|
commands), then an INF parameter cannot be used.
|
||
|
|
|
||
|
|
For style {cylinder}, the c1,c2 params are coordinates in the 2 other
|
||
|
|
dimensions besides the cylinder axis dimension. For dim = x, c1/c2 =
|
||
|
|
y/z; for dim = y, c1/c2 = x/z; for dim = z, c1/c2 = x/y. Thus the
|
||
|
|
third example above specifes a cylinder with its axis in the
|
||
|
|
y-direction located at x = 2.0 and z = 3.0, with a radius of 5.0, and
|
||
|
|
extending in the y-direction from -5.0 to the upper box boundary.
|
||
|
|
|
||
|
|
The {union} style creates a region consisting of the volume of all the
|
||
|
|
listed regions combined. The {intesect} style creates a region
|
||
|
|
consisting of the volume that is common to all the listed regions.
|
||
|
|
|
||
|
|
The {side} keyword determines whether the region is considered to be
|
||
|
|
inside or outside of the specified geometry. Using this keyword in
|
||
|
|
conjunction with {union} and {intersect} regions, complex geometries
|
||
|
|
can be built up. For example, if the interior of two spheres were
|
||
|
|
each defined as regions, and a {union} style with {side} = out was
|
||
|
|
constructed listing the region-IDs of the 2 spheres, the resulting
|
||
|
|
region would be all the volume in the simulation box that was outside
|
||
|
|
both of the spheres.
|
||
|
|
|
||
|
|
The {units} keyword determines the meaning of the distance units used
|
||
|
|
to define the region. A {box} value selects standard distance units
|
||
|
|
as defined by the "units"_units.html command, e.g. Angstroms for units
|
||
|
|
= real or metal. A {lattice} value means the distance units are in
|
||
|
|
cubic lattice spacings. The "lattice"_lattice.html command must first
|
||
|
|
be used to define a lattice.
|
||
|
|
|
||
|
|
[Restrictions:] none
|
||
|
|
|
||
|
|
[Related commands:]
|
||
|
|
|
||
|
|
"lattice"_lattice.html, "create_atoms"_create_atoms.html,
|
||
|
|
"delete_atoms"_delete_atoms.html, "group"_group.html
|
||
|
|
|
||
|
|
[Default:]
|
||
|
|
|
||
|
|
The option defaults are side = in and units = lattice.
|