scale value = no or yes
no = the variable value is the new setting
- yes = the variable value multiplies the original setting
-
- reset value = no or yes
+ yes = the variable value multiplies the original setting
+ reset value = no or yes
no = values will remain altered at the end of a run
yes = reset altered values to their original values at the end of a run
@@ -65,7 +64,11 @@ attributes which can be varied by this fix are discussed below. Many
other fixes can also be used to time-vary simulation parameters,
e.g. the "fix deform" command will change the simulation box
size/shape and the "fix move" command will change atom positions and
-velocities in a prescribed manner.
+velocities in a prescribed manner. Also note that many commands allow
+variables as arguments for specific parameters, if described in that
+manner on their doc pages. An equal-style variable can calculate a
+time-dependent quantity, so this is another way to vary a simulation
+parameter over time.
If N is specified as 0, the specified attributes are only changed once, before the simulation begins. This is all that is needed if the diff --git a/doc/fix_adapt.txt b/doc/fix_adapt.txt index 6c7b6ef356..bd9bc5a9a7 100644 --- a/doc/fix_adapt.txt +++ b/doc/fix_adapt.txt @@ -31,7 +31,7 @@ zero or more keyword/value pairs may be appended :l keyword = {scale} or {reset} :l {scale} value = {no} or {yes} {no} = the variable value is the new setting - {yes} = the variable value multiplies the original setting :pre + {yes} = the variable value multiplies the original setting {reset} value = {no} or {yes} {no} = values will remain altered at the end of a run {yes} = reset altered values to their original values at the end of a run :pre @@ -52,7 +52,11 @@ attributes which can be varied by this fix are discussed below. Many other fixes can also be used to time-vary simulation parameters, e.g. the "fix deform" command will change the simulation box size/shape and the "fix move" command will change atom positions and -velocities in a prescribed manner. +velocities in a prescribed manner. Also note that many commands allow +variables as arguments for specific parameters, if described in that +manner on their doc pages. An equal-style variable can calculate a +time-dependent quantity, so this is another way to vary a simulation +parameter over time. If {N} is specified as 0, the specified attributes are only changed once, before the simulation begins. This is all that is needed if the diff --git a/doc/fix_wall.html b/doc/fix_wall.html index 5e8f1546d9..281d36a005 100644 --- a/doc/fix_wall.html +++ b/doc/fix_wall.html @@ -29,14 +29,18 @@
args = coord epsilon sigma cutoff +
cutoff = distance from wall at which wall-particle interaction is cut off (distance units)
pbc value = yes or no
+ no = invoke the wall constraint in the normal way
+ pbc value = yes or no
yes = allow periodic boundary in a wall dimension
no = require non-perioidic boundaries in any wall dimension
@@ -144,6 +147,16 @@ constant K, and has units (energy/distance^2). The input parameter
spring is at the cutoff. This is a repulsive-only spring since the
interaction is truncated at the cutoff
+For any wall, the epsilon and/or sigma parameter can be specified +as an equal-style variable, in which case it should be +specified as v_name, where name is the variable name. As with a +variable wall position, the variable is evaluated each timestep and +the result becomes the current epsilon or sigma of the wall. +Equal-style variables can specify formulas with various mathematical +functions, and include thermo_style command +keywords for the simulation box parameters and timestep and elapsed +time. Thus it is easy to specify a time-dependent wall interaction. +
IMPORTANT NOTE: For all of the styles, you must insure that r is always > 0 for all particles in the group, or LAMMPS will generate an error. This means you cannot start your simulation with particles at @@ -194,7 +207,8 @@ want.
Here are examples of variable definitions that move the wall position in a time-dependent fashion using equal-style -variables. +variables. The wall interaction parameters (epsilon, +sigma) could be varied with additional variable definitions.
variable ramp equal ramp(0,10)
fix 1 all wall xlo v_ramp 1.0 1.0 2.5
diff --git a/doc/fix_wall.txt b/doc/fix_wall.txt
index 3874587bd0..803aff618e 100644
--- a/doc/fix_wall.txt
+++ b/doc/fix_wall.txt
@@ -25,7 +25,9 @@ face = {xlo} or {xhi} or {ylo} or {yhi} or {zlo} or {zhi} :l
constant = number like 0.0 or -30.0 (distance units)
variable = "equal-style variable"_variable.html like v_x or v_wiggle
epsilon = strength factor for wall-particle interaction (energy or energy/distance^2 units)
+ epsilon can be a variable (see below) :l
sigma = size factor for wall-particle interaction (distance units)
+ sigma can be a variable (see below) :l
cutoff = distance from wall at which wall-particle interaction is cut off (distance units) :pre
zero or more keyword/value pairs may be appended :l
keyword = {units} or {fld} :l
@@ -34,7 +36,7 @@ keyword = {units} or {fld} :l
{box} = the wall position is defined in simulation box units
{fld} value = {yes} or {no}
{yes} = invoke the wall constraint to be compatible with implicit FLD
- {no} = invoke the wall constraint in the normal way :pre
+ {no} = invoke the wall constraint in the normal way
{pbc} value = {yes} or {no}
{yes} = allow periodic boundary in a wall dimension
{no} = require non-perioidic boundaries in any wall dimension :pre
@@ -129,6 +131,16 @@ constant K, and has units (energy/distance^2). The input parameter
spring is at the {cutoff}. This is a repulsive-only spring since the
interaction is truncated at the {cutoff}
+For any wall, the {epsilon} and/or {sigma} parameter can be specified
+as an "equal-style variable"_variable.html, in which case it should be
+specified as v_name, where name is the variable name. As with a
+variable wall position, the variable is evaluated each timestep and
+the result becomes the current epsilon or sigma of the wall.
+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 wall interaction.
+
IMPORTANT NOTE: For all of the styles, you must insure that r is
always > 0 for all particles in the group, or LAMMPS will generate an
error. This means you cannot start your simulation with particles at
@@ -179,7 +191,8 @@ want.
Here are examples of variable definitions that move the wall position
in a time-dependent fashion using equal-style
-"variables"_variable.html.
+"variables"_variable.html. The wall interaction parameters (epsilon,
+sigma) could be varied with additional variable definitions.
variable ramp equal ramp(0,10)
fix 1 all wall xlo v_ramp 1.0 1.0 2.5 :pre