From 2f25e80bf256110cfd3c6d7ef32b9c88f04d5a0c Mon Sep 17 00:00:00 2001 From: sjplimp Date: Thu, 22 Mar 2007 17:05:12 +0000 Subject: [PATCH] git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@430 f3b2605a-c512-4ea7-a41b-209d697bcdaa --- doc/Section_commands.html | 8 +++---- doc/Section_commands.txt | 1 + doc/fix.html | 1 + doc/fix.txt | 1 + doc/fix_nve_noforce.html | 49 +++++++++++++++++++++++++++++++++++++++ doc/fix_nve_noforce.txt | 44 +++++++++++++++++++++++++++++++++++ doc/variable.html | 12 ++++++---- doc/variable.txt | 12 ++++++---- 8 files changed, 114 insertions(+), 14 deletions(-) create mode 100644 doc/fix_nve_noforce.html create mode 100644 doc/fix_nve_noforce.txt diff --git a/doc/Section_commands.html b/doc/Section_commands.html index 7c60c5876a..bd2ecc2ae9 100644 --- a/doc/Section_commands.html +++ b/doc/Section_commands.html @@ -317,10 +317,10 @@ description:
- - - - + + +
addforceaveforceave/spatialave/timebox/relaxcomdepositdrag
efieldenforce2dfreezegran/diaggravitygyrationindentlangevin
lineforcemsdmomentumnphnptnvenve/grannvt
orient/fccplaneforcepoemspourprintrdfrecenterrigid
setforceshakespringspring/rgspring/selftemp/rescaletmduniaxial
viscousvolume/rescalewall/granwall/lj93wall/lj126wall/reflectwiggle +
lineforcemsdmomentumnphnptnvenve/grannve/noforce
nvtorient/fccplaneforcepoemspourprintrdfrecenter
rigidsetforceshakespringspring/rgspring/selftemp/rescaletmd
uniaxialviscousvolume/rescalewall/granwall/lj93wall/lj126wall/reflectwiggle
diff --git a/doc/Section_commands.txt b/doc/Section_commands.txt index 87661968e4..3ef3f16dfc 100644 --- a/doc/Section_commands.txt +++ b/doc/Section_commands.txt @@ -392,6 +392,7 @@ description: "npt"_fix_npt.html, "nve"_fix_nve.html, "nve/gran"_fix_nve_gran.html, +"nve/noforce"_fix_nve_noforce.html, "nvt"_fix_nvt.html, "orient/fcc"_fix_orient_fcc.html, "planeforce"_fix_planeforce.html, diff --git a/doc/fix.html b/doc/fix.html index bb2f0485ec..27f719bb2a 100644 --- a/doc/fix.html +++ b/doc/fix.html @@ -86,6 +86,7 @@ made to the old fix via the fix_modify command.
  • fix npt - constant NPT time integration via Nose/Hoover
  • fix nve - constant NVE time integration
  • fix nve/gran - NVE time integration for granular systems +
  • fix nve/noforce - NVE integration without forces (v only)
  • fix nvt - constant NVT time integration via Nose/Hoover
  • fix orient/fcc - add grain boundary migration force
  • fix planeforce - constrain atoms to move in a plane diff --git a/doc/fix.txt b/doc/fix.txt index acef1f1bcf..33ac885603 100644 --- a/doc/fix.txt +++ b/doc/fix.txt @@ -86,6 +86,7 @@ Here is an alphabetic list of fix styles defined in LAMMPS: "fix nve"_fix_nve.html - constant NVE time integration "fix nve/gran"_fix_nve_gran.html - NVE time integration for \ granular systems +"fix nve/noforce"_fix_nve_noforce.html - NVE integration without forces (v only) "fix nvt"_fix_nvt.html - constant NVT time integration via Nose/Hoover "fix orient/fcc"_fix_orient_fcc.html - add grain boundary migration force "fix planeforce"_fix_planeforce.html - constrain atoms to move in a plane diff --git a/doc/fix_nve_noforce.html b/doc/fix_nve_noforce.html new file mode 100644 index 0000000000..b5a0bfca74 --- /dev/null +++ b/doc/fix_nve_noforce.html @@ -0,0 +1,49 @@ + +
    LAMMPS WWW Site - LAMMPS Documentation - LAMMPS Commands +
    + + + + + + +
    + +

    fix nve/noforce command +

    +

    Syntax: +

    +
    fix ID group-ID nve 
+
    + +

    Examples: +

    +
    fix 3 wall nve/noforce 
+
    +

    Description: +

    +

    Perform updates of position, but not velocity for atoms in the group +each timestep. In other words, the force on the atoms is ignored and +their velocity is not updated. The atom's velocities are used to +update their positions. +

    +

    This can be useful for wall atoms, when you set their velocities, but +want the wall to move (or stay stationary) in a prescribed fashion. +

    +

    This can also be accomplished via the fix setforce +command, but with fix nve/noforce, the forces on the wall atoms are +unchanged, and can thus be printed out by the dump command +or queried with an equal-style variable that uses the +fcm() group command to compute the total force on the group of atoms. +

    +

    Restrictions: none +

    +

    Related commands: +

    +

    fix nvt, fix npt +

    +

    Default: none +

    + diff --git a/doc/fix_nve_noforce.txt b/doc/fix_nve_noforce.txt new file mode 100644 index 0000000000..3667e41701 --- /dev/null +++ b/doc/fix_nve_noforce.txt @@ -0,0 +1,44 @@ +"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 + +fix nve/noforce command :h3 + +[Syntax:] + +fix ID group-ID nve :pre + +ID, group-ID are documented in "fix"_fix.html command +nve/noforce = style name of this fix command :ul + +[Examples:] + +fix 3 wall nve/noforce :pre + +[Description:] + +Perform updates of position, but not velocity for atoms in the group +each timestep. In other words, the force on the atoms is ignored and +their velocity is not updated. The atom's velocities are used to +update their positions. + +This can be useful for wall atoms, when you set their velocities, but +want the wall to move (or stay stationary) in a prescribed fashion. + +This can also be accomplished via the "fix setforce"_fix_setforce.html +command, but with fix nve/noforce, the forces on the wall atoms are +unchanged, and can thus be printed out by the "dump"_dump.html command +or queried with an equal-style "variable"_variable.html that uses the +fcm() group command to compute the total force on the group of atoms. + +[Restrictions:] none + +[Related commands:] + +"fix nvt"_fix_nvt.html, "fix npt"_fix_npt.html + +[Default:] none diff --git a/doc/variable.html b/doc/variable.html index c87b5cc927..e03c58bfeb 100644 --- a/doc/variable.html +++ b/doc/variable.html @@ -29,8 +29,9 @@ thermo keywords = vol, ke, press, etc from thermo_style math functions = add(x,y), sub(x,y), mult(x,y), div(x,y), neg(x), pow(x,y), exp(x), ln(x), sqrt(x) - group functions = mass(group), charge(group), xcm(group,dim), - vcm(group,dim), bound(group,xmin), gyration(group) + group functions = mass(group), charge(group), + xcm(group,dim), vcm(group,dim), fcm(group,dim), + bound(group,xmin), gyration(group) atom vectors for equal = mass[N], x[N], y[N], z[N], vx[N], vy[N], vz[N], fx[N], fy[N], fz[N] @@ -196,7 +197,7 @@ variables; the syntax of Atom vector references is different. Number 0.2, 1.0e20, -15.4, etc Thermo keywords vol, pe, ebond, etc Math functions add(x,y), sub(x,y), mult(x,y), div(x,y), neg(x), pow(x,y), exp(x), ln(x), sqrt(x) -Group functions mass(ID), charge(ID), xcm(ID,dim), vcm(ID,dim), bound(ID,dir), gyration(ID) +Group functions mass(ID), charge(ID), xcm(ID,dim), vcm(ID,dim), fcm(ID,dim) bound(ID,dir), gyration(ID) Atom vectors for equal mass[N], x[N], y[N], z[N], vx[N], vy[N], vz[N], fx[N], fy[N], fz[N] Atom vectors for atom mass[], x[], y[], z[], vx[], vy[], vz[], fx[], fy[], fz[] Compute references c_ID[0], c_ID[N] @@ -220,8 +221,9 @@ group-ID. The dim argument is x or y or z. The argument is xmin, xmax, ymin, ymax, zmin, or zmax. The group functions mass() and charge() are the total mass and charge of the group of atoms. Xcm() and vcm() return components of the position -and velocity of the center of mass of the group. Bound() returns the -min/max of a particular coordinate for all atoms in the group. +and velocity of the center of mass of the group. Fcm() returns a +component of the total force on the group of atoms. Bound() returns +the min/max of a particular coordinate for all atoms in the group. Gyration() computes the radius-of-gyration of the group of atoms. See the fix gyration command for the formula.

    diff --git a/doc/variable.txt b/doc/variable.txt index d8cd925472..1c4e8250ed 100644 --- a/doc/variable.txt +++ b/doc/variable.txt @@ -24,8 +24,9 @@ style = {index} or {loop} or {world} or {universe} or {uloop} or {equal} or {ato thermo keywords = vol, ke, press, etc from "thermo_style"_thermo_style.html math functions = add(x,y), sub(x,y), mult(x,y), div(x,y), neg(x), pow(x,y), exp(x), ln(x), sqrt(x) - group functions = mass(group), charge(group), xcm(group,dim), - vcm(group,dim), bound(group,xmin), gyration(group) + group functions = mass(group), charge(group), + xcm(group,dim), vcm(group,dim), fcm(group,dim), + bound(group,xmin), gyration(group) atom vectors for {equal} = mass\[N\], x\[N\], y\[N\], z\[N\], vx\[N\], vy\[N\], vz\[N\], fx\[N\], fy\[N\], fz\[N\] @@ -190,7 +191,7 @@ Number: 0.2, 1.0e20, -15.4, etc Thermo keywords: vol, pe, ebond, etc Math functions: add(x,y), sub(x,y), mult(x,y), div(x,y), \ neg(x), pow(x,y), exp(x), ln(x), sqrt(x) -Group functions: mass(ID), charge(ID), xcm(ID,dim), vcm(ID,dim), \ +Group functions: mass(ID), charge(ID), xcm(ID,dim), vcm(ID,dim), fcm(ID,dim) \ bound(ID,dir), gyration(ID) Atom vectors for {equal}: mass\[N\], x\[N\], y\[N\], z\[N\], \ vx\[N\], vy\[N\], vz\[N\], \ @@ -218,8 +219,9 @@ group-ID. The {dim} argument is {x} or {y} or {z}. The {dir} argument is {xmin}, {xmax}, {ymin}, {ymax}, {zmin}, or {zmax}. The group functions mass() and charge() are the total mass and charge of the group of atoms. Xcm() and vcm() return components of the position -and velocity of the center of mass of the group. Bound() returns the -min/max of a particular coordinate for all atoms in the group. +and velocity of the center of mass of the group. Fcm() returns a +component of the total force on the group of atoms. Bound() returns +the min/max of a particular coordinate for all atoms in the group. Gyration() computes the radius-of-gyration of the group of atoms. See the "fix gyration"_fix_gyration.html command for the formula.