From 983e8bb110a6faeab4675137ccccb51e3f986739 Mon Sep 17 00:00:00 2001 From: Steve Plimpton <sjplimp@sandia.gov> Date: Tue, 11 Sep 2018 11:36:37 -0600 Subject: [PATCH] doc page clarifications --- doc/src/fix_shake.txt | 6 ++++-- doc/src/minimize.txt | 13 +++++++++---- 2 files changed, 13 insertions(+), 6 deletions(-) diff --git a/doc/src/fix_shake.txt b/doc/src/fix_shake.txt index 77bb5794f6..5c11f96b98 100644 --- a/doc/src/fix_shake.txt +++ b/doc/src/fix_shake.txt @@ -214,8 +214,10 @@ which can lead to poor energy conservation. You can test for this in your system by running a constant NVE simulation with a particular set of SHAKE parameters and monitoring the energy versus time. -SHAKE or RATTLE should not be used to constrain an angle at 180 degrees -(e.g. linear CO2 molecule). This causes numeric difficulties. +SHAKE or RATTLE should not be used to constrain an angle at 180 +degrees (e.g. linear CO2 molecule). This causes numeric difficulties. +You can use "fix rigid or fix rigid/small"_fix_rigid.html instead to +make a linear molecule rigid. [Related commands:] none diff --git a/doc/src/minimize.txt b/doc/src/minimize.txt index 910fc7f821..73858fc249 100644 --- a/doc/src/minimize.txt +++ b/doc/src/minimize.txt @@ -216,10 +216,10 @@ The "fix box/relax"_fix_box_relax.html command can be used to apply an external pressure to the simulation box and allow it to shrink/expand during the minimization. -Only a few other fixes (typically those that apply force constraints) -are invoked during minimization. See the doc pages for individual -"fix"_fix.html commands to see which ones are relevant. Current -examples of fixes that can be used include: +Only a few other fixes (typically those that add forces) are invoked +during minimization. See the doc pages for individual "fix"_fix.html +commands to see which ones are relevant. Current examples of fixes +that can be used include: "fix addforce"_fix_addforce.html "fix addtorque"_fix_addtorque.html @@ -242,6 +242,11 @@ you MUST enable the "fix_modify"_fix_modify.html {energy} option for that fix. The doc pages for individual "fix"_fix.html commands specify if this should be done. +NOTE: The minimizers in LAMMPS do not allow for bonds (or angles, etc) +to be held fixed while atom coordinates are being relaxed, e.g. via +"fix shake"_fix_shake.html or "fix rigid"_fix_rigid.html. See more +info in the Restrictions section below. + :line [Restrictions:] -- GitLab