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Joined: Sep 2008
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rssc Offline OP
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Dear All,

Currently, I am doing calculations on Molecular Crystals. My first job is to MINImize the crystalline structure, after this calculation, I obtain a new set of "a", "b", and "c" cell parameters.

Now, since the cell parameters have changed, the FFTX, FFTY, and FFTZ parameters of the "ewald summation" should change as well. Does CHARMM automatically update these parameters (i.e., FFTX, FFTY, and FFTZ)? Or, do I have to update (by hand) the FFTX, FFTY, and FFTZ after the unit cell optimization?

Thanks for your help,
RSSC

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rmv Online Content
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The P-M Ewald FFTX, etc. grid values must be explicitly specified in the input. There are some possibilities for automating the choice, using preselected grid values (which meet the 2,3,5 rule) and some IF logic to test the cell edge and make a choice.


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