periodic cell has become too small for original patch grid!

From: ydhuang2727 (ydhuang2727_at_163.com)
Date: Tue Nov 18 2008 - 02:54:42 CST

 Hey, everyone!
 
I come across an error like,
 periodic cell has become too small for original patch grid!
 
 Although, i have known that PMEGridSize should be chosen so that it can be factorized by 2, 3 or 5, still am i not determined on how to setup PMEGridSize according to cellBasisVector and i am, totally, not sure if my setup is right or wrong only based on sush a single rule.
Firstly, please have a look at the following setup:
 # Periodic Boundary Conditions
cellBasisVector1 93.0 0. 0.
cellBasisVector2 0. 82.4 0.
cellBasisVector3 0. 0. 90.5
cellOrigin -8.449 54.259 48.939
wrapAll on
 
#I got the cellBasisVector poorly by hand, using Mouse/Label/Bond in VMD main menu. Is there any other good method for this?

# PME (for full-system periodic electrostatics)
PME yes
PMEGridSizeX 96
PMEGridSizeY 81
PMEGridSizeZ 90
 
Herein, my confusion is:
can PMEGridSize be bigger or smaller than cellBasisVector?
how do i get the right values?
 
Thanks !!
Good day!
 
Dong,

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