Edit screening function in MEAM

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1

Hi,
      I want to edit the screening function used in MEAM. LAMMPS has hard coded functional form as [1-(1-x)^4]^2. I want to change it to [1-(1-x)^6]^2. I did go through "meam_dens_init.F" file in the lib/meam/ directory and made changes in "fcut" and "dfcut" subroutines accordingly. Are there any other palces, I need to make changes?

Thanks
Priyank Shukla

2

Hi Priyank,

I think those are the only places that change needs to be made, but you should also be aware that the fcut and dfcut subroutines are used not just the for screening function as it transitions between Cmin and Cmax, but also the for the smooth cutoff function on a pair of atoms as the interatomic distance approaches the cutoff radius (the function controlled by the rc and delr parameters in the input file). If it's not your intent to change both of these cutoffs, you may need to introduce a new pair of subroutines and apply them only for the screening function.

Regards,
Greg

Greg Wagner
Sandia National Laboratories
P.O. Box 969 MS 9409 Livermore, CA 94551
Tel: (925) 294-2180 Fax: (925) 294-3410
Email: [email protected]...

3

Thanks Greg,
                        I did not consider that. I guess, I will introduce a new subroutines.

Regards
Priyank