If the quantity you are trying to compute is sensitive to differences of the order of 4*10^{-5} A in atomic positions, you have chosen an hopeless task, in my opinion.
Paolo Il 28/dic/2016 02:18 PM, "Pablo García Risueño" <garcia.risu...@gmail.com> ha scritto: > Dear professor > > Thank you very much for your reply. The differences are important in this > case, my final calculated quantities are very sensitive to these optimized > positions. Should I change any of the ***conv_thr variables, or other > variable, to have the same result for same inputs? > > Is there any random number in the algorithm of relax calculations, can we > be sure that different outputs with the same input are not due to any bug? > > Thank you very much. Best regards. > > 2016-12-28 14:10 GMT+01:00 Paolo Giannozzi <p.gianno...@gmail.com>: > >> The differences you find are very small. Nothing to worry about in my >> opinion. >> >> By the way: Davidson diagonalization is typically faster than CG; do not >> specify incompatible options in K_POINTS (gamma or automatic, not both; >> gamma should be used unless you have a good reason not to) >> >> Paolo >> >> Il 28/dic/2016 01:46 PM, "Pablo García Risueño" <garcia.risu...@gmail.com> >> ha scritto: >> > >> > Dear Espresso community >> > >> > I have one problem that is important for me; it is somewhat surprising. >> I run geometry optimization (relax) calculations with pw.x with identical >> input files, and I obtain rather different final coordinates. The problem >> does not happen if ecutwfc is 30, but it does appear for cutoffs of 60, 80 >> or 90. Below one can see the exact input file, and examples of the >> difference between the final coordinates for both runs (both run with >> identical input) for given cutoffs. >> > >> > Could anybody give me a clue on the origin of the problem, and how to >> solve it? >> > >> > Thank you very much. Best regards. >> > >> > >> > >> > Input file: >> > >> > >> > >> > &CONTROL >> > >> > calculation = 'relax', >> > >> > restart_mode = 'from_scratch', >> > >> > prefix='', >> > >> > outdir = './', >> > >> > pseudo_dir = '/path_xxx/PP/', >> > >> > forc_conv_thr = 1.0D-6 , >> > >> > etot_conv_thr = 1.0D-8 , >> > >> > / >> > >> > &system >> > >> > ibrav = 0, a=18.0, >> > >> > nat= 26, ntyp= 2, >> > >> > ecutwfc = 30d0, >> > >> > nbnd = 100, >> > >> > / >> > >> > &electrons >> > >> > conv_thr = 1.0e-9, >> > >> > mixing_beta = 0.7, >> > >> > mixing_mode = 'plain', >> > >> > diagonalization = 'cg' >> > >> > / >> > >> > &IONS >> > >> > / >> > >> > >> > >> > ATOMIC_SPECIES >> > >> > C 12.0107 C.pz-vbc.UPF >> > >> > H 1.007825035 H.pz-vbc.UPF >> > >> > >> > >> > ATOMIC_POSITIONS { angstrom } >> > >> > C 8.891700e+00 8.891700e+00 8.891700e+00 >> > >> > C 9.783400e+00 9.783400e+00 8.000000e+00 >> > >> > C 9.783400e+00 8.000000e+00 9.783400e+00 >> > >> > C 8.000000e+00 9.783400e+00 9.783400e+00 >> > >> > C 8.891700e+00 1.067510e+01 1.067510e+01 >> > >> > C 1.067510e+01 1.067510e+01 8.891700e+00 >> > >> > C 1.067510e+01 8.891700e+00 1.067510e+01 >> > >> > C 9.783400e+00 1.156680e+01 9.783400e+00 >> > >> > C 9.783400e+00 9.783400e+00 1.156680e+01 >> > >> > C 1.156680e+01 9.783400e+00 9.783400e+00 >> > >> > H 8.391700e+00 8.391700e+00 8.391700e+00 >> > >> > H 7.500000e+00 1.028340e+01 9.283400e+00 >> > >> > H 7.500000e+00 9.283400e+00 1.028340e+01 >> > >> > H 9.283400e+00 1.028340e+01 7.500000e+00 >> > >> > H 1.028340e+01 9.283400e+00 7.500000e+00 >> > >> > H 9.283400e+00 7.500000e+00 1.028340e+01 >> > >> > H 1.028340e+01 7.500000e+00 9.283400e+00 >> > >> > H 9.283400e+00 1.206680e+01 9.283400e+00 >> > >> > H 1.206680e+01 9.283400e+00 9.283400e+00 >> > >> > H 9.283400e+00 9.283400e+00 1.206680e+01 >> > >> > H 8.391700e+00 1.117510e+01 1.117510e+01 >> > >> > H 1.117510e+01 1.117510e+01 8.391700e+00 >> > >> > H 1.117510e+01 8.391700e+00 1.117510e+01 >> > >> > H 1.028340e+01 1.206680e+01 1.028340e+01 >> > >> > H 1.028340e+01 1.028340e+01 1.206680e+01 >> > >> > H 1.206680e+01 1.028340e+01 1.028340e+01 >> > >> > >> > >> > >> > >> > CELL_PARAMETERS {cubic} >> > >> > 1.00 0.00 0.00 >> > >> > 0.00 1.00 0.00 >> > >> > 0.00 0.00 1.00 >> > >> > >> > >> > K_POINTS {gamma} {automatic} >> > >> > 1 1 1 0 0 0 >> > >> > >> > >> > >> > >> > The program is run with >> > >> > >> > >> > mpirun -np 32 /path_xxx/pw.x >> > >> > >> > >> > Final coordinates: The first two rows for ecutwfc=30 for two runs with >> identical input are: >> > >> > ATOMIC_POSITIONS (angstrom) >> > C 8.898432121 8.898432121 8.898432121 >> > C 9.783306562 9.783306562 8.019670107 >> > >> > ATOMIC_POSITIONS (angstrom) >> > C 8.898432121 8.898432121 8.898432121 >> > C 9.783306562 9.783306562 8.019670109 >> > >> > >> > Final coordinates: The first two rows for ecutwfc=60 for two runs with >> identical input are: >> > >> > ATOMIC_POSITIONS (angstrom) >> > C 8.904988579 8.904988579 8.904988579 >> > C 9.783426086 9.783426086 8.031809869 >> > >> > ATOMIC_POSITIONS (angstrom) >> > C 8.904962246 8.904962246 8.904962246 >> > C 9.783425401 9.783425401 8.031847251 >> > >> > -- >> > -- >> > >> > Dr. Pablo García Risueño >> > >> > Institut für Physikalische Chemie, Universität Hamburg, Grindelallee >> 117, 20146 Hamburg >> > >> > Tel. +49 040 42 83 84 82 7 >> > >> > _______________________________________________ >> > Pw_forum mailing list >> > Pw_forum@pwscf.org >> > http://pwscf.org/mailman/listinfo/pw_forum >> >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum@pwscf.org >> http://pwscf.org/mailman/listinfo/pw_forum >> > > > > -- > -- > > Dr. Pablo García Risueño > > Institut für Physikalische Chemie, Universität Hamburg, Grindelallee 117, > 20146 Hamburg > > Tel. +49 040 42 83 84 82 7 > > _______________________________________________ > Pw_forum mailing list > Pw_forum@pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum >
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