Dear Ghosh, Thanks for you explanation. Now I got it. I have another problem. After running 'min ....', I got a structure with very small force. However, when I do another calculation with the structure I got, the total force on each atom becomes very large. What is the reason for this?
Yundi On Mon, Sep 26, 2011 at 7:44 PM, Ghosh SUDDHASATTWA <ssghosh at igcar.gov.in>wrote: > Dear Yundi, > If I understand your question correctly, then just by doing step 1, you > cannot get energy minimum but by doing the following > 1. Optimize lattice parameters > 2. use optimized lattice parameters and then min_lapw > 3. Use optimized lattice parameters and optimized atomic positions and get > ENE (including -so or any other options) > > Only after step 3, can you say that you have energy minimum. > > -----Original Message----- > From: wien-bounces at zeus.theochem.tuwien.ac.at > [mailto:wien-bounces at zeus.theochem.tuwien.ac.at] On Behalf Of Yundi Quan > Sent: Monday, September 26, 2011 9:25 PM > To: A Mailing list for WIEN2k users > Subject: Re: [Wien] phonon calculation > > In the second step, what if the total energy changes with the internal > structure so that the so-called energy minimum found in step one is no > longer a energy minimum? > > Yundi > > 2011/9/26 Ghosh SUDDHASATTWA <ssghosh at igcar.gov.in>: > > Dear Yundi, > > What I follow is > > 1. do volume or c/a, b/a relaxation depending on your structure > > 2. Use the optimized lattice parameters to do min_lapw > > 3. Use the optimized lattice parameters and atomic positions to define > the > > supercell in Phonon software > > 4. import the d45 file from phonon to wien2k > > 5. run phonon.job in wien2k > > 6. get the force file and export it to phonon > > 7. get the phonon dispersion > > > > you can use -fc 1.0 in min_lapw as well as in phonon. you can then try > -fc > > 0.50 and then so on > > > > SG > > > > ________________________________ > > From: wien-bounces at zeus.theochem.tuwien.ac.at > > [mailto:wien-bounces at zeus.theochem.tuwien.ac.at] On Behalf Of Yundi Quan > > Sent: Monday, September 26, 2011 3:41 PM > > To: A Mailing list for WIEN2k users > > Subject: [Wien] phonon calculation > > > > In order to get the correct input structure for phonon calculation, I > need > > to first find the structure with minimal force. How much force is small > > enough? Is 1.0 mRy/bohr small enough? (I only want to calculate the > phonon > > at gamma point to see whether the system is stable or not at gamma point) > > Should I first carry out internal structure minimization or crystal > > structure minimization? > > > > > > Yundi > > _______________________________________________ > > Wien mailing list > > Wien at zeus.theochem.tuwien.ac.at > > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > > > > > _______________________________________________ > Wien mailing list > Wien at zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > > _______________________________________________ > Wien mailing list > Wien at zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20110926/3552a3bb/attachment.htm>