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how to find force acting on an image

Posted: Fri Nov 26, 2010 7:30 am
by stractor
Dear all,
I use regular NEB method to investigate atom diffusion process. I encounter a convergence problem. I read some papers on NEB methed and knew that the total force acting on an image is the sum of the spring force along the local tangent and the true fore perpendicular to the local tangent. I also note that the OUTCAR file gives "energy of chain is (eV)", "tangential force (eV/A)', "CHAIN-FORCE (eV/Angst)", "CHAIN+TOTAL (eV/Angst)", "g(Force)" and "g(Stress)". What is total force acting on an image (How to find this total force in OUTCAR)? If I set EDIFFG=-0.05 for NEB calculation, does it means that the chain convergence criteria is the fore actiong on an image are less than 0.05 eV/A?

PS: I use regular NEB implanted in VASP 4.6.

Re: how to find force acting on an image

Posted: Tue Apr 26, 2011 6:50 am
by cenwanglai
Strator, I have the same problem. Have you got your answer?

Re: how to find force acting on an image

Posted: Tue Apr 26, 2011 2:56 pm
by graeme
The 'CHAIN+TOTAL (eV/Angst)' is the total force acting on the image.

If you set ediffg=-0.05, the calculation will converge when the RMS NEB force on each atom in each image is less than 0.05 eV/Ang.