[QE-users] Gamma point phonon calculation is not consistent
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 = (0.0 0.0 0.0 ) ** 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_3uI freq ( 2 - 2) = -1.1 [cm-1] --> B_1uI freq ( 3 - 3) = 0.9 [cm-1] --> B_2uI freq ( 4 - 4) = 97.7 [cm-1] --> B_3uI freq ( 5 - 5) =188.1 [cm-1] --> B_3gR freq ( 6 - 6) =221.5 [cm-1] --> B_2gR 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_1gR freq ( 10 - 10) =425.1 [cm-1] --> B_2gR freq ( 11 - 11) =452.7 [cm-1] --> A_g R freq ( 12 - 12) =462.8 [cm-1] --> B_1uI This results comes from Gamma point in several q point calculation. q = (0.0 0.0 0.0 ) ** 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_1uI freq ( 2 - 2) = 17.7 [cm-1] --> B_3uI freq ( 3 - 3) = 18.0 [cm-1] --> B_2uI freq ( 4 - 4) = 97.9 [cm-1] --> B_2uI freq ( 5 - 5) =188.5 [cm-1] --> B_2gR freq ( 6 - 6) =221.5 [cm-1] --> B_3gR 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_1gR freq ( 10 - 10) =425.3 [cm-1] --> B_3gR freq ( 11 - 11) =452.7 [cm-1] --> A_g R freq ( 12 - 12) =463.0 [cm-1] --> B_1uI Why these two parts are not same? The structure I already optimised. TW. Department of Physics Tohoku Unviersity Email: wang1968...@163.com ___ Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
[QE-users] How to plot phonon band structure with LO-TO splitting
Dear QE users, I have attempted to see the LO-TO splitting in polar material (AlAS: SG216). My LO-TO splitting values are in the tune with what I have seen in various tutorials. # mode [cm-1][THz] IR 1 0.00 0. 0. 2 0.00 0. 0. 3 0.00 0. 0. 4*352.99 10.5824*5.3390 5*352.99 10.5824*5.3390 6*392.54 11.7681*5.3390 Without LO-TO splitting, the phonon band structure is here: https://we.tl/t-eU2SfLYlMu (from MP) where we can see that LO-TO at Gamma point are degenerate. When we account for the non-analytic corrections, the LO-TO branch at Gamma point should split (by ~1THz as above). Could someone please guide me how to plot phonon band structure with the LO-TO splitting? I can plot the regular phonon band structure with q2r.x > matdyn.x but could not find a way to plot with the above corrections. Regards K.C. Bhamu CSIR-NCL, Pune India ___ Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
[QE-users] Problem with Plotting Fermi Surfaces
Hi, I am calculating band structure and fermi surfaces for a narrow-gap semiconductor using LDA, full relativistic, NC PPs. When I plot band structure I see a band gap of about 0.04eV, but When I want to plot Fermi Surfaces using Xcrysden, I saw some overlap between Valance and Conduction band, there is some contribution from valance bands at Fermi level. Could you please guide me what is the problem with that? I follow the instruction in example02 for plotting Fermi surfaces for my optimized parameters and atomic positions: First a SCF calculation, Then a non-SCF (calculation: nscf, dense grid without any shift and tetrahedral method) and then post-processing with fs.x. Thank you so much! Best, Shima ___ Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
