These are fix styles contributed by users, which can be used if diff --git a/doc/fix_wall.html b/doc/fix_wall.html index 7b05bd158c..c0638b4e6d 100644 --- a/doc/fix_wall.html +++ b/doc/fix_wall.html @@ -50,33 +50,34 @@ fix zwalls all wall/colloid zlo 0.0 1.0 1.0 0.858 zhi 40.0 1.0 1.0 0.858
Bound the simulation domain on one or more of its faces with a flat wall that interacts with the atoms in the group by generating a force -on the atom in a direction perpendicular to the wall. The energy E of +on the atom in a direction perpendicular to the wall. The energy of wall-particle interactions depends on the style.
-For style wall/lj93, the energy is given by the 9/3 potential: +
For style wall/lj93, the energy E is given by the 9/3 potential:
For style wall/lj126, the energy is given by the 12/6 potential: +
For style wall/lj126, the energy E is given by the 12/6 potential:
For style wall/colloid, the energy is given by an integrated form of +
For style wall/colloid, the energy E is given by an integrated form of the pair_style colloid potential:
In all cases, r is the distance from the particle to the wall -coord, and Rc is the cutoff distance at which the particle and -wall no longer interact, as specified in the command. The energy of -the wall potential is shifted so that the energy of the wall-particle -interaction is 0.0 at the cutoff distance. +
In all cases, r is the distance from the particle to the wall at +position coord, and Rc is the cutoff distance at which the +particle and wall no longer interact. The energy of the wall +potential is shifted so that the wall-particle interaction energy is +0.0 at the cutoff distance.
For the wall/lj93 and wall/lj126 styles, epsilon and sigma are the usual Lennard-Jones parameters, which determine the strength and size of the particle as it interacts with the wall. Note that this -sigma may be different than any sigma values defined for a pair -style that computes particle-particle interactions. +epsilon and sigma may be different than any epsilon or sigma +values defined for a pair style that computes particle-particle +interactions.
The wall/lj93 interaction is derived by integrating over a 3d half-lattice of Lennard-Jones 12/6 particles. The wall/lj126 @@ -92,18 +93,18 @@ center to the wall.
The wall/colloid interaction is derived by integrating over constituent LJ particles of size sigma within the colloid particle -and a 3d half-lattice of Lennard-Jones 12/6 particles with the same -sigma in the wall. +and a 3d half-lattice of Lennard-Jones 12/6 particles of size sigma +in the wall.
If the vel keyword is specified, the position of all walls will move during the simulation in a perpendicular direction, based on their -initial position (coord), the specified velocity (vel), and the time +initial coord position, the specified velocity vel, and the time elapsed since the beginning of the simulation. See the note below about making a wall move continuously across multiple runs. A positive velocity means each wall moves inward, towards the center of -the box. I.e. an xlo wall will move in the +x direction; an xhi -wall will move in the -x direction. A negative velocity means each -wall moves outward, away from the center of the box. If you want +the box. I.e. an xlo wall will move in the +x direction and an +xhi wall will move in the -x direction. A negative velocity means +each wall moves outward, away from the center of the box. If you want different walls to move with different velocities, then you need to use multiple fix wall commands.
@@ -113,13 +114,13 @@ direction, according to the equation:position = pos0 + A sin (omega * delta)-
where pos0 is the position at the time the beginning of the -simulation, A is the amplitude, omega is 2 PI / period, and -delta is the time elapsed since the beginning of the simulation. -See the note below about making a wall oscillate continuously across -multiple runs. A positive amplitude means each wall initially moves -inward, towards the center of the box. I.e. an xlo wall will move -initially in the +x direction; an xhi wall will move in the -x +
where pos0 is the position at the beginning of the simulation, A +is the amplitude, omega is 2 PI / period, and delta is the +time elapsed since the beginning of the simulation. See the note +below about making a wall oscillate continuously across multiple runs. +A positive amplitude means each wall initially moves inward, towards +the center of the box. I.e. an xlo wall will move initially in the ++x direction and an xhi wall will move initially in the -x direction. A negative velocity means each wall moves initially outward, away from the center of the box. If you want different walls to oscillate with different amplitudes or periods, then you need to @@ -135,14 +136,18 @@ fix to add the energy of interaction between atoms and each wall to the system's potential energy as part of thermodynamic output.
-This fix computes a scalar energy and a 3-vector of forces (on the
-walls), which can be accessed by various output
+ This fix computes a scalar energy and a 6-length vector of forces (one
+force magnitude per wall), which can be accessed by various output
commands. The scalar and vector values
calculated by this fix are "extensive", meaning they scale with the
-number of atoms in the simulation. Note that if you define multiple
-walls, then the energy and force will be summed over all the walls.
-If you want the energy/force on a per-wall basis, you need to use
-multiple fix wall commands.
+number of atoms in the simulation. Note that the scalar energy is the
+sum of interactions with all defined walls. If you want the energy on
+a per-wall basis, you need to use multiple fix wall commands. The 6
+vector quantities are the force on the xlo wall, the xhi wall,
+ylo, yhi, zlo, zhi. These values will only be non-zero if the
+corresponding wall is defined. Note that an outward force on a wall
+will be a negative value for lo walls and a positive value for hi
+walls.
This fix can change the position of each wall, due to the vel or
wiggle keywords, continuously over multiple runs, using the start
diff --git a/doc/fix_wall.txt b/doc/fix_wall.txt
index 1c4728a6d6..5894ba8256 100644
--- a/doc/fix_wall.txt
+++ b/doc/fix_wall.txt
@@ -126,14 +126,18 @@ fix to add the energy of interaction between atoms and each wall to
the system's potential energy as part of "thermodynamic
output"_thermo_style.html.
-This fix computes a scalar energy and a 3-vector of forces (on the
-walls), which can be accessed by various "output
+This fix computes a scalar energy and a 6-length vector of forces (one
+force magnitude per wall), which can be accessed by various "output
commands"_Section_howto.html#4_15. The scalar and vector values
calculated by this fix are "extensive", meaning they scale with the
-number of atoms in the simulation. Note that if you define multiple
-walls, then the energy and force will be summed over all the walls.
-If you want the energy/force on a per-wall basis, you need to use
-multiple fix wall commands.
+number of atoms in the simulation. Note that the scalar energy is the
+sum of interactions with all defined walls. If you want the energy on
+a per-wall basis, you need to use multiple fix wall commands. The 6
+vector quantities are the force on the {xlo} wall, the {xhi} wall,
+{ylo}, {yhi}, {zlo}, {zhi}. These values will only be non-zero if the
+corresponding wall is defined. Note that an outward force on a wall
+will be a negative value for {lo} walls and a positive value for {hi}
+walls.
This fix can change the position of each wall, due to the {vel} or
{wiggle} keywords, continuously over multiple runs, using the {start}