From b72f03d427a8f3ea49c680a125a3ec579e6b6c13 Mon Sep 17 00:00:00 2001
From: sjplimp <sjplimp@f3b2605a-c512-4ea7-a41b-209d697bcdaa>
Date: Sat, 5 Jan 2013 00:48:13 +0000
Subject: [PATCH] git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@9240
 f3b2605a-c512-4ea7-a41b-209d697bcdaa

---
 doc/fix_heat.html | 14 ++++++++++++++
 doc/fix_heat.txt  | 14 +++++++++++++-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/doc/fix_heat.html b/doc/fix_heat.html
index e871f5f484..44295c0cce 100644
--- a/doc/fix_heat.html
+++ b/doc/fix_heat.html
@@ -23,6 +23,8 @@
 
 <LI>eflux = rate of heat addition or subtraction (energy/time units) 
 
+<LI>eflux can be a variable (see below) 
+
 <LI>zero or more keyword/value pairs may be appended to args 
 
 <LI>keyword = <I>region</I>  
@@ -35,6 +37,7 @@
 <P><B>Examples:</B>
 </P>
 <PRE>fix 3 qin heat 1 1.0
+fix 3 qin heat 10 v_flux
 fix 4 qout heat 1 -1.0 region top 
 </PRE>
 <P><B>Description:</B>
@@ -62,6 +65,17 @@ time the fix is invoked.  If heat is subtracted from the system too
 aggressively so that the group's kinetic energy would go to zero,
 LAMMPS halts with an error message.
 </P>
+<P>The <I>eflux</I> parameter can be specified as an equal-style
+<A HREF = "variable.html">variable</A>.  If the value is a variable, it should be
+specified as v_name, where name is the variable name.  In this case,
+the variable will be evaluated each timestep, and its value used to
+determine the flux.
+</P>
+<P>Equal-style variables can specify formulas with various mathematical
+functions, and include <A HREF = "thermo_style.html">thermo_style</A> command
+keywords for the simulation box parameters and timestep and elapsed
+time.  Thus it is easy to specify a time-dependent flux.
+</P>
 <P>Fix heat is different from a thermostat such as <A HREF = "fix_nh.html">fix nvt</A>
 or <A HREF = "fix_temp_rescale.html">fix temp/rescale</A> in that energy is
 added/subtracted continually.  Thus if there isn't another mechanism
diff --git a/doc/fix_heat.txt b/doc/fix_heat.txt
index b6c3ee3560..51a26b4278 100644
--- a/doc/fix_heat.txt
+++ b/doc/fix_heat.txt
@@ -16,6 +16,7 @@ ID, group-ID are documented in "fix"_fix.html command :ulb,l
 heat = style name of this fix command :l
 N = add/subtract heat every this many timesteps :l
 eflux = rate of heat addition or subtraction (energy/time units) :l
+eflux can be a variable (see below) :l
 zero or more keyword/value pairs may be appended to args :l
 keyword = {region}  :l
   {region} value = region-ID
@@ -25,6 +26,7 @@ keyword = {region}  :l
 [Examples:]
 
 fix 3 qin heat 1 1.0
+fix 3 qin heat 10 v_flux
 fix 4 qout heat 1 -1.0 region top :pre
 
 [Description:]
@@ -52,6 +54,17 @@ time the fix is invoked.  If heat is subtracted from the system too
 aggressively so that the group's kinetic energy would go to zero,
 LAMMPS halts with an error message.
 
+The {eflux} parameter can be specified as an equal-style
+"variable"_variable.html.  If the value is a variable, it should be
+specified as v_name, where name is the variable name.  In this case,
+the variable will be evaluated each timestep, and its value used to
+determine the flux.
+
+Equal-style variables can specify formulas with various mathematical
+functions, and include "thermo_style"_thermo_style.html command
+keywords for the simulation box parameters and timestep and elapsed
+time.  Thus it is easy to specify a time-dependent flux.
+
 Fix heat is different from a thermostat such as "fix nvt"_fix_nh.html
 or "fix temp/rescale"_fix_temp_rescale.html in that energy is
 added/subtracted continually.  Thus if there isn't another mechanism
@@ -90,4 +103,3 @@ minimization"_minimize.html.
 temp/region"_compute_temp_region.html
 
 [Default:] none
-