Page Menu
Home
c4science
Search
Configure Global Search
Log In
Files
F94969245
compute_temp_region.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
Wed, Dec 11, 19:41
Size
2 KB
Mime Type
text/html
Expires
Fri, Dec 13, 19:41 (1 d, 21 h)
Engine
blob
Format
Raw Data
Handle
22905681
Attached To
rLAMMPS lammps
compute_temp_region.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 temp/region command
</H3>
<P><B>
Syntax:
</B>
</P>
<PRE>
compute ID group-ID temp/region region-ID
</PRE>
<UL><LI>
ID, group-ID are documented in
<A
HREF =
"compute.html"
>
compute
</A>
command
<LI>
temp/region = style name of this compute command
<LI>
region-ID = ID of region to use for choosing atoms
</UL>
<P><B>
Examples:
</B>
</P>
<PRE>
temperature mine flow region boundary
</PRE>
<P><B>
Description:
</B>
</P>
<P>
Define a computation that calculates the temperature of a group of
atoms in a geometric region. This can be useful for thermostatting
one portion of the simulation box. E.g. a McDLT simulation where one
side is cooled, and the other side is heated. A compute of this style
can be used by any command that computes a temperature,
e.g.
<A
HREF =
"thermo_modify.html"
>
thermo_modify
</A>
,
<A
HREF =
"fix_temp_rescale.html"
>
fix
temp/rescale
</A>
, etc.
</P>
<P>
Note that a
<I>
region
</I>
-style temperature can be used to thermostat with
<A
HREF =
"fix_temp_rescale.html"
>
fix temp/rescale
</A>
or
<A
HREF =
"fix_langevin.html"
>
fix
langevin
</A>
, but should probably not be used with
Nose/Hoover style fixes (
<A
HREF =
"fix_nvt.html"
>
fix nvt
</A>
,
<A
HREF =
"fix_npt.html"
>
fix
npt
</A>
, or
<A
HREF =
"fix_nph.html"
>
fix nph
</A>
), if the
degrees-of-freedom included in the computed T varies with time.
</P>
<P>
The temperature is calculated by the formula KE = dim/2 N k T, where
KE = total kinetic energy of the group of atoms (sum of 1/2 m v^2),
dim = 2 or 3 = dimensionality of the simulation, N = number of atoms
in both the group and region, k = Boltzmann constant, and T =
temperature.
</P>
<P>
A 6-component kinetic energy tensor is also calculated by this compute
for use in the computation of a pressure tensor. The formula for the
components of the tensor is the same as the above formula, except that
v^2 is replaced by vx * vy for the xy component, etc.
</P>
<P>
The number of atoms contributing to the temperature is compute each
time the temperature is evaluated since it is assumed atoms can
enter/leave the region. Thus there is no need to use the
<I>
dynamic
</I>
option of the
<A
HREF =
"compute_modify.html"
>
compute_modify
</A>
command for this
compute style.
</P>
<P>
Unlike other compute styles that calculate temperature, this compute
does NOT currently subtract out degrees-of-freedom due to fixes that
constrain molecular motion, such as
<A
HREF =
"fix_shake.html"
>
fix shake
</A>
and
<A
HREF =
"fix_rigid.html"
>
fix rigid
</A>
. If needed the subtracted
degrees-of-freedom can be altered using the
<I>
extra
</I>
option of the
<A
HREF =
"compute_modify.html"
>
compute_modify
</A>
command.
</P>
<P><B>
Restrictions:
</B>
none
</P>
<P><B>
Related commands:
</B>
</P>
<P><A
HREF =
"compute_temp.html"
>
compute temp
</A>
,
<A
HREF =
"compute_pressure.html"
>
compute
pressure
</A>
</P>
<P><B>
Default:
</B>
none
</P>
</HTML>
Event Timeline
Log In to Comment