Dear Prof. Gerhard and Stefaan, As the system is complex so to save my wall time, I need a confirmation what I am following.
In a fresh calculation, after a structure relaxation, I have done C/A optimization [VARY C/A RATIO with CONSTANT VOLUME and B/A (orthorh lattice)]. The new optimization values are given below. It gives Minimum value of C/A is = 0.983596 so this means that (C/A)_new =983596 (say "X") C_new=(X)*(A_new). #A_new is taken from below set of data. Should I go this way or A should be the old one? Now update this C_new in struct file and then go for B/A optimization. followed by volume optimization to get optimised A. Minimum value of C/A is = 0.983596 >>> minmum value of C/A Minimum value of ENE is = -339059.101281 Ry ========================================================== Value of A is = 14.66061 bohr ; 7.75806 Ang >> A_new Value of B is = 21.69275 bohr ; 11.47931 Ang Value of C is = 14.42012 bohr ; 7.63080 Ang ========================================================== Initial value of C/A is = 0.973598 Conv. Unit Cell Vol = 4586.0140 bohr^3 ; 679.5773 Ang^3 ========================================================== Regards Bhamu On Fri, Oct 13, 2017 at 5:40 PM, Stefaan Cottenier < stefaan.cotten...@ugent.be> wrote: > No, not really. You have three (unit cell) degrees of freedom: E(a,b,c). > Or similarly E(V, b/a, c/a) (with V=a*b*c). The different options in > optimize_lapw give you a series of unit cells with either different values > of V (and b/a and c/a constant), different values of b/a (and V and c/a > constant) and different values of c/a (and V and b/a constant). These are > three slices through the energy landscape. By finding the energy minimum > along one slice, fix it, then go on with the next slice, etc. … you can > gradually approach the absolute energy minimum. It might take several > iterations through this scheme if your starting cell is far away from the > minimum. Best is to start first with the degree of freedom that affects > energy most (usually the volume). > > > > Stefaan > > > > > > *Van:* Wien [mailto:wien-boun...@zeus.theochem.tuwien.ac.at] *Namens *Dr. > K. C. Bhamu > *Verzonden:* vrijdag 13 oktober 2017 14:04 > *Aan:* A Mailing list for WIEN2k users <wien@zeus.theochem.tuwien.ac.at> > *Onderwerp:* Re: [Wien] optimization of an orthorhombic cell > > > > Thank you very much for a hint. > > I thought the value obtained from "VARY C/A RATIO with CONSTANT VOLUME and > B/A (orthorh lattice)" are well optimised then why I do need to optimise > all of them again. > > Now I see, B/A scaling will give us optimised b, then C/A scaling will > give us optimised C and finally optimised v(=a*b*c) will give us optimised > "a". > > Using optimised a,b,c structure relaxation will be done. > > > > > > I should be fine to optimised an orthorhombic cell. Is it? > > > > > > > > > Regards > > Bhamu > > > > On Fri, Oct 13, 2017 at 11:18 AM, Fecher, Gerhard <fec...@uni-mainz.de> > wrote: > > you have three quantities V=a*b*c, b=a*(b/a) and c=a*(c/a) > so what is the problem ? > > Ciao > Gerhard > > DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy: > "I think the problem, to be quite honest with you, > is that you have never actually known what the question is." > > ==================================== > Dr. Gerhard H. Fecher > Institut of Inorganic and Analytical Chemistry > Johannes Gutenberg - University > 55099 Mainz > and > Max Planck Institute for Chemical Physics of Solids > 01187 Dresden > ________________________________________ > Von: Wien [wien-boun...@zeus.theochem.tuwien.ac.at] im Auftrag von Dr. K. > C. Bhamu [kcbham...@gmail.com] > Gesendet: Freitag, 13. Oktober 2017 00:42 > An: A Mailing list for WIEN2k users > Betreff: Re: [Wien] optimization of an orthorhombic cell > > Dear List, > > > Could you please help me to get optimize lattice parameters from the > procedure that I followed as mentioned below: > > > > The procedure is a four-step task what I am following: > > The original lattice parameters were: a, b, c=16.763005, 24.803600, > 16.320431 >> vol 6785.64777697697 bohr^3. > > > 1. VARY C/A RATIO with CONSTANT VOLUME and B/A (orthorh lattice) > > getting below optimized data: > ========================================================== > Lowest point on X-axis is = -1.615800 > Minimum value of B/A is = 1.455755 > Minimum value of ENE is = -339059.104498 Ry > ========================================================== > Value of A is = 16.85428 bohr ; 8.91890 Ang > Value of B is = 24.53569 bohr ; 12.98373 Ang > Value of C is = 16.40929 bohr ; 8.68342 Ang > ========================================================== > Initial value of B/A is = 1.479663 > Conv. Unit Cell Vol = 6785.7557 bohr^3 ; **********Ang^ > > > 2. Volume optimization using option 1 in "x optimize" and then > calculating new volume from eplot option. > > > Query: Step two is giving optimized volume but I do not know how to > calculate lattices parameters from a single volume > value for the next step "VARY C/A RATIO with CONSTANT VOLUME and B/A > (orthorh lattice)"? > > > The original cell volume and lattice parameters are mentioned at the > beginning. > > and the new volume from step two is: 6815.3427 bohr^3 > > > > The above same query is for the remaining process: > > 3. optimization of C/A > > 4. optimization of V. > > > *5 At the final step I will do structural relaxation (min_.....). > > > Could you please advice me how to proceed? > > > > Kind regards, > Bhamu > > > > > > _______________________________________________ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at<mailto:Wien@zeus.theochem.tuwien.ac.at> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien<ht > tps://urldefense.proofpoint.com/v2/url?u=http-3A__zeus. > theochem.tuwien.ac.at_mailman_listinfo_wien&d=DwMFaQ&c= > yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_ > T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=jaERo6- > xRrI1rqWCrakeE5WmWmBA9HsvfQ0pWtZpamE&s=k9TTzTtvPnftD3rW739Eaq2h0Q3Pge > 41KqyrRFQbNbI&e=> > SEARCH the MAILING-LIST at: http://www.mail-archive.com/ > wien@zeus.theochem.tuwien.ac.at/index.html<https:// > urldefense.proofpoint.com/v2/url?u=http-3A__www.mail- > 2Darchive.com_wien-40zeus.theochem.tuwien.ac.at_index.html&d=DwMFaQ&c= > yHlS04HhBraes5BQ9ueu5zKhE7rtNXt_d012z2PA6ws&r=U_ > T4PL6jwANfAy4rnxTj8IUxm818jnvqKFdqWLwmqg0&m=jaERo6- > xRrI1rqWCrakeE5WmWmBA9HsvfQ0pWtZpamE&s=R687MZ- > ZkJaGHltsY7XUF5LWZwcPAM4v4dFTheFPQds&e=> > > > > _______________________________________________ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at<mailto: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 > > > _______________________________________________ > 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 > > > > _______________________________________________ > 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 > >
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