There are two sets of "differences" in your calculations: - the three lowest frequencies of the acoustic mode - symmetry labels B_2 and B_3. I don't know about the latter, but the former difference reflects an algorithmic difference: the Gamma-only code (phcg.x) imposes acoustic sum rule during the calculation, while the ordinary phonon code (ph.x) doesn't. Nothing to worry about.
Paolo On Wed, Oct 30, 2019 at 3:16 AM wang1968000 <[email protected]> wrote: > Hi. QE users. > I have calculate Gamma point phonon and phonon dispersion on black > phosphorus. > But the phonon modes are not same in only Gamma point calculation and > several q point calculations. > > This is the results coming from only Gamma point calculation. > Diagonalizing the dynamical matrix > > q = ( 0.000000000 0.000000000 0.000000000 ) > > ************************************************************************** > freq ( 1) = -0.038897 [THz] = -1.297458 [cm-1] > freq ( 2) = -0.031677 [THz] = -1.056638 [cm-1] > freq ( 3) = 0.027926 [THz] = 0.931519 [cm-1] > freq ( 4) = 2.928955 [THz] = 97.699418 [cm-1] > freq ( 5) = 5.638698 [THz] = 188.086708 [cm-1] > freq ( 6) = 6.639162 [THz] = 221.458590 [cm-1] > freq ( 7) = 10.953491 [THz] = 365.369131 [cm-1] > freq ( 8) = 12.684841 [THz] = 423.120746 [cm-1] > freq ( 9) = 12.722708 [THz] = 424.383866 [cm-1] > freq ( 10) = 12.745234 [THz] = 425.135234 [cm-1] > freq ( 11) = 13.570613 [THz] = 452.666939 [cm-1] > freq ( 12) = 13.874216 [THz] = 462.794044 [cm-1] > ************************************************************************** > > Mode symmetry, D_2h (mmm) point group: > > freq ( 1 - 1) = -1.3 [cm-1] --> B_3u I > freq ( 2 - 2) = -1.1 [cm-1] --> B_1u I > freq ( 3 - 3) = 0.9 [cm-1] --> B_2u I > freq ( 4 - 4) = 97.7 [cm-1] --> B_3u I > freq ( 5 - 5) = 188.1 [cm-1] --> B_3g R > freq ( 6 - 6) = 221.5 [cm-1] --> B_2g R > freq ( 7 - 7) = 365.4 [cm-1] --> A_g R > freq ( 8 - 8) = 423.1 [cm-1] --> A_u > freq ( 9 - 9) = 424.4 [cm-1] --> B_1g R > freq ( 10 - 10) = 425.1 [cm-1] --> B_2g R > freq ( 11 - 11) = 452.7 [cm-1] --> A_g R > freq ( 12 - 12) = 462.8 [cm-1] --> B_1u I > > > This results comes from Gamma point in several q point calculation. > q = ( 0.000000000 0.000000000 0.000000000 ) > > ************************************************************************** > freq ( 1) = 0.294821 [THz] = 9.834157 [cm-1] > freq ( 2) = 0.531839 [THz] = 17.740255 [cm-1] > freq ( 3) = 0.538183 [THz] = 17.951848 [cm-1] > freq ( 4) = 2.934902 [THz] = 97.897792 [cm-1] > freq ( 5) = 5.651273 [THz] = 188.506166 [cm-1] > freq ( 6) = 6.641297 [THz] = 221.529834 [cm-1] > freq ( 7) = 10.953478 [THz] = 365.368700 [cm-1] > freq ( 8) = 12.689602 [THz] = 423.279546 [cm-1] > freq ( 9) = 12.724636 [THz] = 424.448167 [cm-1] > freq ( 10) = 12.750003 [THz] = 425.294313 [cm-1] > freq ( 11) = 13.570944 [THz] = 452.677974 [cm-1] > freq ( 12) = 13.879876 [THz] = 462.982823 [cm-1] > ************************************************************************** > > Mode symmetry, D_2h (mmm) point group: > > freq ( 1 - 1) = 9.8 [cm-1] --> B_1u I > freq ( 2 - 2) = 17.7 [cm-1] --> B_3u I > freq ( 3 - 3) = 18.0 [cm-1] --> B_2u I > freq ( 4 - 4) = 97.9 [cm-1] --> B_2u I > freq ( 5 - 5) = 188.5 [cm-1] --> B_2g R > freq ( 6 - 6) = 221.5 [cm-1] --> B_3g R > freq ( 7 - 7) = 365.4 [cm-1] --> A_g R > freq ( 8 - 8) = 423.3 [cm-1] --> A_u > freq ( 9 - 9) = 424.4 [cm-1] --> B_1g R > freq ( 10 - 10) = 425.3 [cm-1] --> B_3g R > freq ( 11 - 11) = 452.7 [cm-1] --> A_g R > freq ( 12 - 12) = 463.0 [cm-1] --> B_1u I > > > Why these two parts are not same? > The structure I already optimised. > > TW. > Department of Physics > Tohoku Unviersity > Email: [email protected] > > > > > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users -- Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche, Univ. Udine, via delle Scienze 208, 33100 Udine, Italy Phone +39-0432-558216, fax +39-0432-558222
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