>From a Google search "*Acceptable results* means a variance of less than plus or minus two (2) standard deviations".
Remembering that (depending upon functional) there is a nett contraction/expansion, what is the standard deviation of your measurements and is your calculation within two sigma ? (And don't email back asking if it is, be a scientist and answer it yourself.) On Wed, Aug 12, 2020 at 9:00 AM shamik chakrabarti <shamik15041...@gmail.com> wrote: > Dear Prof. Laurence Marks Sir, > > Thank you for your email. > Sir, we have obtained the following results by using the above procedure; > > Expt. Theory > a=12.134 a=11.8071 > b= 3.87 b=3.8838 > c= 11.23 c=10.9285 > > Whether these are acceptable results? > > with regards, > > > On Wed, 12 Aug 2020 at 18:53, Laurence Marks <laurence.ma...@gmail.com> > wrote: > >> I have an impression that you have asked before about optimization, in >> fact many times! >> >> A question you should ask yourself is what are you trying to achieve? DFT >> is not a perfect theory, and while you can improve the agreement with >> experiment using better (and slower) methods, in general experiment is more >> accurate. >> >> If your calculations are close to experiment, e.g. atoms at positions >> maybe 0.01 Angers off, that is all you can expect. >> >> If, for instance, the positions are 0.1 Angers off, and/or it is a metal >> whereas in experiment it is an insulator, then something is very wrong. No >> amount of lattice optimization is going to help. >> >> So, my question to you is are you killing defenseless electrons in a >> quest to overfit data, or is there a reason? >> >> _____ >> Professor Laurence Marks >> "Research is to see what everybody else has seen, and to think what >> nobody else has thought", Albert Szent-Gyorgi >> www.numis.northwestern.edu >> >> On Wed, Aug 12, 2020, 08:11 shamik chakrabarti <shamik15041...@gmail.com> >> wrote: >> >>> Also after obtaining the c/a optimized struct file with optimized >>> lattice parameter & nearly optimized atomic coordinates for a hexagonal >>> system I do a force minimization by keeping the lattice parameter intact >>> (as obtained from c/a optimization curve). Whether this will give a wrong >>> minima? >>> >>> with regards, >>> >>> On Wed, 12 Aug 2020 at 18:17, shamik chakrabarti < >>> shamik15041...@gmail.com> wrote: >>> >>>> Dear Prof. Blaha, >>>> >>>> I have done some calculations by keeping both lines >>>> active. What it does; >>>> (!) It runs first runsp_lapw -ec 0.0001 for a given struct file >>>> (2) After getting the energy convergence, it does the force >>>> minimization for the given structure & saves the successive struct files as >>>> case_i.scf for i=1,2.... >>>> (3) after getting the force optimized structure it saves the optimized >>>> struct files in case....._default.struct. >>>> >>>> What I do I take the optimized struct file which is near the minima >>>> i.e, say case_coa____-5.00 _default .struct for next calculation & put the >>>> lattice parameters in this file by calculating it by hand from c/a >>>> optimized curve. >>>> >>>> Is this give the wrong minimum? >>>> >>>> Looking forward to your response in this regard. >>>> >>>> with regards, >>>> >>>> On Wed, 12 Aug 2020 at 17:59, Peter Blaha <pbl...@theochem.tuwien.ac.at> >>>> wrote: >>>> >>>>> You certainly don't want both lines active. >>>>> >>>>> For a simultaneous optimization of internal coordinates, the >>>>> recommended >>>>> command in optimize.job is to add -min to the run-command: >>>>> >>>>> runsp_lapw -nlvdw -fc 1 -ec 0.001 -min >>>>> >>>>> An older alternative (usually not recommended) is: >>>>> >>>>> min -I -j "runsp_lapw -nlvdw -I -fc 1.0 -i 40 " >>>>> >>>>> >>>>> On 8/12/20 11:03 AM, shamik chakrabarti wrote: >>>>> > Dear Wien2k users, >>>>> > I have edited the optimized.job by >>>>> > uncommenting the following two lines for running simultaneous >>>>> > optimization of atomic coordinates with a,b,c: >>>>> > >>>>> > runsp_lapw -nlvdw -ec 0.0001 >>>>> > >>>>> > min -I -j "runsp_lapw -nlvdw -I -fc 1.0 -i 40 " >>>>> > >>>>> > Is this method is correct? >>>>> > >>>>> > Looking forward to hearing from you. >>>>> > >>>>> > Thanks in advance >>>>> > >>>>> > with regards, >>>>> > >>>>> > -- >>>>> > Dr. Shamik Chakrabarti >>>>> > Research Fellow >>>>> > Department of Physics >>>>> > Indian Institute of Technology Patna >>>>> > Bihta-801103 >>>>> > Patna >>>>> > Bihar, India >>>>> > >>>>> > _______________________________________________ >>>>> > Wien mailing list >>>>> > Wien@zeus.theochem.tuwien.ac.at >>>>> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >>>>> <https://urldefense.com/v3/__http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien__;!!Dq0X2DkFhyF93HkjWTBQKhk!DI73f-Re7inuxswiG0HG_WW_8qHNkinbKZvm5h73PnAPN071cMfFjL8iMl1H3LfS79oWIw$> >>>>> > SEARCH the MAILING-LIST at: >>>>> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html >>>>> <https://urldefense.com/v3/__http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html__;!!Dq0X2DkFhyF93HkjWTBQKhk!DI73f-Re7inuxswiG0HG_WW_8qHNkinbKZvm5h73PnAPN071cMfFjL8iMl1H3LdFLbcbAw$> >>>>> > >>>>> >>>>> -- >>>>> >>>>> P.Blaha >>>>> >>>>> -------------------------------------------------------------------------- >>>>> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna >>>>> Phone: +43-1-58801-165300 FAX: +43-1-58801-165982 >>>>> Email: bl...@theochem.tuwien.ac.at WIEN2k: http://www.wien2k.at >>>>> <https://urldefense.com/v3/__http://www.wien2k.at__;!!Dq0X2DkFhyF93HkjWTBQKhk!DI73f-Re7inuxswiG0HG_WW_8qHNkinbKZvm5h73PnAPN071cMfFjL8iMl1H3LckRMua-Q$> >>>>> WWW: http://www.imc.tuwien.ac.at/TC_Blaha >>>>> <https://urldefense.com/v3/__http://www.imc.tuwien.ac.at/TC_Blaha__;!!Dq0X2DkFhyF93HkjWTBQKhk!DI73f-Re7inuxswiG0HG_WW_8qHNkinbKZvm5h73PnAPN071cMfFjL8iMl1H3Ld00IoRBg$> >>>>> >>>>> -------------------------------------------------------------------------- >>>>> _______________________________________________ >>>>> Wien mailing list >>>>> Wien@zeus.theochem.tuwien.ac.at >>>>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >>>>> <https://urldefense.com/v3/__http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien__;!!Dq0X2DkFhyF93HkjWTBQKhk!DI73f-Re7inuxswiG0HG_WW_8qHNkinbKZvm5h73PnAPN071cMfFjL8iMl1H3LfS79oWIw$> >>>>> SEARCH the MAILING-LIST at: >>>>> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html >>>>> <https://urldefense.com/v3/__http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html__;!!Dq0X2DkFhyF93HkjWTBQKhk!DI73f-Re7inuxswiG0HG_WW_8qHNkinbKZvm5h73PnAPN071cMfFjL8iMl1H3LdFLbcbAw$> >>>>> >>>> >>>> >>>> -- >>>> Dr. Shamik Chakrabarti >>>> Research Fellow >>>> Department of Physics >>>> Indian Institute of Technology Patna >>>> Bihta-801103 >>>> Patna >>>> Bihar, India >>>> >>> >>> >>> -- >>> Dr. Shamik Chakrabarti >>> Research Fellow >>> Department of Physics >>> Indian Institute of Technology Patna >>> Bihta-801103 >>> Patna >>> Bihar, India >>> _______________________________________________ >>> Wien mailing list >>> Wien@zeus.theochem.tuwien.ac.at >>> >>> https://urldefense.com/v3/__http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien__;!!Dq0X2DkFhyF93HkjWTBQKhk!DI73f-Re7inuxswiG0HG_WW_8qHNkinbKZvm5h73PnAPN071cMfFjL8iMl1H3LfS79oWIw$ >>> SEARCH the MAILING-LIST at: >>> https://urldefense.com/v3/__http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html__;!!Dq0X2DkFhyF93HkjWTBQKhk!DI73f-Re7inuxswiG0HG_WW_8qHNkinbKZvm5h73PnAPN071cMfFjL8iMl1H3LdFLbcbAw$ >>> >> _______________________________________________ >> Wien mailing list >> Wien@zeus.theochem.tuwien.ac.at >> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >> <https://urldefense.com/v3/__http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien__;!!Dq0X2DkFhyF93HkjWTBQKhk!C5rbn-duCdrEWGrPWaO-FtTUDAMicPgCPwaGFpyhJQdM6uZmguV-mhnRLnw88DsK0YR_OA$> >> SEARCH the MAILING-LIST at: >> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html >> <https://urldefense.com/v3/__http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html__;!!Dq0X2DkFhyF93HkjWTBQKhk!C5rbn-duCdrEWGrPWaO-FtTUDAMicPgCPwaGFpyhJQdM6uZmguV-mhnRLnw88Du5k1H4qA$> >> > > > -- > Dr. Shamik Chakrabarti > Research Fellow > Department of Physics > Indian Institute of Technology Patna > Bihta-801103 > Patna > Bihar, India > _______________________________________________ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at > > https://urldefense.com/v3/__http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien__;!!Dq0X2DkFhyF93HkjWTBQKhk!C5rbn-duCdrEWGrPWaO-FtTUDAMicPgCPwaGFpyhJQdM6uZmguV-mhnRLnw88DsK0YR_OA$ > SEARCH the MAILING-LIST at: > https://urldefense.com/v3/__http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html__;!!Dq0X2DkFhyF93HkjWTBQKhk!C5rbn-duCdrEWGrPWaO-FtTUDAMicPgCPwaGFpyhJQdM6uZmguV-mhnRLnw88Du5k1H4qA$ > -- Professor Laurence Marks Department of Materials Science and Engineering Northwestern University www.numis.northwestern.edu Corrosion in 4D: www.numis.northwestern.edu/MURI Co-Editor, Acta Cryst A "Research is to see what everybody else has seen, and to think what nobody else has thought" Albert Szent-Gyorgi
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