Can you tell me how to extract lattice parameter as a function of pressure? I didn't find it in case.eosfit as mentioned here http://www.mail-archive.com/wien%40zeus.theochem.tuwien.ac.at/msg04276.html

`It would be trivial to do this for a crystal that is entirely determined`

`by the volume (for instance, bcc iron): you calculate energy for a few`

`volumes, do the Birch-Murnaghan fit by eosfit, look for the volume vs.`

`pressure data in case.eosfitb, and convert the volume to lattice parameter.`

`It becomes somewhat more complicated when you have internal degrees of`

`freedom (let's still assume a cubic crystal for the time being). Again`

`calculate the total energy for a set of volumes. But for every volume,`

`the internal positions should now be optimized first. Once you have done`

`that, the procedure is the same as before, and you can get the lattice`

`parameters out of the volume.`

`Now drop the requirement of a cubic crystal. Take an orthorhombic one`

`(with or without internal degrees of freedom). Again you need the total`

`energy for a set of volumes. But for every volume you need optimize`

`internal parameters and the three lattice parameters (with the`

`restriction that the volume is kept constant). From these optimizations,`

`you will know what the relation between volume and the three different`

`lattice parameters is. From the fitted volume-pressure relation, you can`

`get any of the lattice parameters as a function of pressure.`

Stefaan

After x eosfit, in the case.eosfit, I can only find three colums, which I think corresponding to volum, energy and pressure. But no lattice constant information. I can't find any lattice constant information in case.outputeos either. I guess eosfit6 probably can do this job, however, I don't know how to use it. Before doing x eosfit, I did, parabolfit_lapw, but it always gives me errors. (see blow) I hope you can give me some idea. Thanks in advance. What I have already done, 1) do x optimize and create 36 cases. 2) run optimize.job with "save_lapw -d optimize ${i}" which saves all my data into directory optimize. 3) grepline :ENE "optimize/*scf" 1 >> case.analysis grepline :VOL "optimize/*scf" 1 >> case.analysis 4) eplot_lapw -t vol This step gives me the plot Energy vs Vol. 5) x eosfit 6) parabolfit_lapw -t 2 -f optimize -scf 'optimize/*.scf' : This step gives error like this ls: No match. ls: No match. optimize.ene and optimize.latparam generated ERROR IN OPENING UNIT: 10 FILENAME: ZrPSe.ene STATUS: old FORM:formatted OPEN FAILED 0.0u 0.0s 0:00.00 0.0% 0+0k 0+0io 0pf+0w _______________________________________________ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html

-- Stefaan Cottenier Center for Molecular Modeling (CMM) & Department of Materials Science and Engineering (DMSE) Ghent University Tech Lane Ghent Science Park – Campus A building 903 BE-9052 Zwijnaarde Belgium http://molmod.ugent.be http://www.ugent.be/ea/dmse/en email: stefaan.cotten...@ugent.be my conference talks on Youtube: http://goo.gl/P2b1Hs for China: http://i.youku.com/cottenierlectures _______________________________________________ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html