[Pw_forum] negative frequencies during phonon calculations
C.H. Hu
chaohao.mse at gmail.com
Thu Oct 25 10:30:37 CEST 2007
Dear Pwscf users,
I performed gamma-point phonon calculation for my system only including some
light elements. Some negative frequencies appear as following. The
structure has been optimized first and the nscf calculation was also
performed. Does the negative frequencies indicate the structural
instability? or how to eliminate these imaginary frequencies during my
following calculations?
=========
q = ( 0.000000000 0.000000000 0.000000000 )
**************************************************************************
omega( 1) = -3.014004 [THz] = -100.537026 [cm-1]
omega( 2) = -1.833969 [THz] = -61.175042 [cm-1]
omega( 3) = -1.568539 [THz] = -52.321189 [cm-1]
omega( 4) = -1.362118 [THz] = -45.435661 [cm-1]
omega( 5) = -0.979698 [THz] = -32.679419 [cm-1]
omega( 6) = 3.631786 [THz] = 121.144148 [cm-1]
omega( 7) = 4.565661 [THz] = 152.295057 [cm-1]
omega( 8) = 4.870748 [THz] = 162.471753 [cm-1]
omega( 9) = 5.926574 [THz] = 197.690558 [cm-1]
omega(10) = 6.692205 [THz] = 223.229420 [cm-1]
omega(11) = 6.751437 [THz] = 225.205202 [cm-1]
omega(12) = 7.152446 [THz] = 238.581500 [cm-1]
omega(13) = 7.290775 [THz] = 243.195689 [cm-1]
omega(14) = 7.583548 [THz] = 252.961623 [cm-1]
omega(15) = 7.848509 [THz] = 261.799816 [cm-1]
omega(16) = 8.216032 [THz] = 274.059149 [cm-1]
omega(17) = 8.450907 [THz] = 281.893782 [cm-1]
omega(18) = 8.617843 [THz] = 287.462209 [cm-1]
omega(19) = 8.874576 [THz] = 296.025963 [cm-1]
omega(20) = 9.106260 [THz] = 303.754152 [cm-1]
omega(21) = 9.776634 [THz] = 326.115571 [cm-1]
omega(22) = 9.846084 [THz] = 328.432188 [cm-1]
omega(23) = 10.441744 [THz] = 348.301414 [cm-1]
omega(24) = 10.901272 [THz] = 363.629712 [cm-1]
omega(25) = 11.120174 [THz] = 370.931537 [cm-1]
omega(26) = 11.296950 [THz] = 376.828190 [cm-1]
omega(27) = 11.744897 [THz] = 391.770187 [cm-1]
omega(28) = 11.823415 [THz] = 394.389308 [cm-1]
omega(29) = 12.284723 [THz] = 409.776965 [cm-1]
omega(30) = 12.879001 [THz] = 429.600078 [cm-1]
omega(31) = 13.104238 [THz] = 437.113223 [cm-1]
omega(32) = 13.295358 [THz] = 443.488354 [cm-1]
omega(33) = 13.386218 [THz] = 446.519146 [cm-1]
omega(34) = 13.536055 [THz] = 451.517199 [cm-1]
omega(35) = 13.571174 [THz] = 452.688634 [cm-1]
omega(36) = 14.064683 [THz] = 469.150452 [cm-1]
omega(37) = 14.556450 [THz] = 485.554120 [cm-1]
omega(38) = 14.667300 [THz] = 489.251729 [cm-1]
omega(39) = 15.110352 [THz] = 504.030430 [cm-1]
omega(40) = 15.395285 [THz] = 513.534849 [cm-1]
omega(41) = 16.043631 [THz] = 535.161476 [cm-1]
omega(42) = 16.936124 [THz] = 564.932033 [cm-1]
omega(43) = 18.733204 [THz] = 624.876561 [cm-1]
omega(44) = 18.876424 [THz] = 629.653928 [cm-1]
omega(45) = 19.992373 [THz] = 666.878205 [cm-1]
omega(46) = 21.505666 [THz] = 717.356559 [cm-1]
omega(47) = 21.617840 [THz] = 721.098322 [cm-1]
omega(48) = 22.309307 [THz] = 744.163333 [cm-1]
omega(49) = 23.662551 [THz] = 789.303000 [cm-1]
omega(50) = 24.061062 [THz] = 802.595969 [cm-1]
omega(51) = 24.064277 [THz] = 802.703198 [cm-1]
omega(52) = 25.648159 [THz] = 855.536168 [cm-1]
omega(53) = 26.862084 [THz] = 896.028637 [cm-1]
omega(54) = 26.984089 [THz] = 900.098318 [cm-1]
omega(55) = 28.413367 [THz] = 947.774196 [cm-1]
omega(56) = 28.483349 [THz] = 950.108578 [cm-1]
omega(57) = 28.903442 [THz] = 964.121470 [cm-1]
omega(58) = 29.425892 [THz] = 981.548629 [cm-1]
omega(59) = 29.797340 [THz] = 993.938893 [cm-1]
omega(60) = 30.194172 [THz] = 1007.175875 [cm-1]
omega(61) = 30.533468 [THz] = 1018.493632 [cm-1]
omega(62) = 30.805908 [THz] = 1027.581303 [cm-1]
omega(63) = 31.041973 [THz] = 1035.455634 [cm-1]
omega(64) = 32.094778 [THz] = 1070.573675 [cm-1]
omega(65) = 33.759643 [THz] = 1126.107965 [cm-1]
omega(66) = 33.969486 [THz] = 1133.107616 [cm-1]
omega(67) = 36.434092 [THz] = 1215.318565 [cm-1]
omega(68) = 36.726631 [THz] = 1225.076683 [cm-1]
omega(69) = 39.522021 [THz] = 1318.321478 [cm-1]
omega(70) = 39.623203 [THz] = 1321.696562 [cm-1]
omega(71) = 40.034020 [THz] = 1335.400026 [cm-1]
omega(72) = 40.044563 [THz] = 1335.751729 [cm-1]
omega(73) = 50.292137 [THz] = 1677.576257 [cm-1]
omega(74) = 50.298606 [THz] = 1677.792065 [cm-1]
omega(75) = 51.050051 [THz] = 1702.857719 [cm-1]
omega(76) = 51.176742 [THz] = 1707.083716 [cm-1]
omega(77) = 53.131701 [THz] = 1772.294552 [cm-1]
omega(78) = 53.564853 [THz] = 1786.743033 [cm-1]
omega(79) = 53.946325 [THz] = 1799.467683 [cm-1]
omega(80) = 54.547644 [THz] = 1819.525644 [cm-1]
omega(81) = 55.855114 [THz] = 1863.138433 [cm-1]
omega(82) = 56.009839 [THz] = 1868.299538 [cm-1]
omega(83) = 56.878920 [THz] = 1897.289172 [cm-1]
omega(84) = 56.962499 [THz] = 1900.077075 [cm-1]
omega(85) = 57.147227 [THz] = 1906.238980 [cm-1]
omega(86) = 57.294672 [THz] = 1911.157244 [cm-1]
omega(87) = 58.113524 [THz] = 1938.471399 [cm-1]
omega(88) = 58.186280 [THz] = 1940.898280 [cm-1]
omega(89) = 60.420046 [THz] = 2015.409202 [cm-1]
omega(90) = 60.431210 [THz] = 2015.781574 [cm-1]
**************************************************************************
=========
Regards,
C.H.
--
============================
C.H. Hu
Postdoctoral fellow
Chimie et Physico-Chimie appliquees
Institut Francais du Petrole (IFP)
Rueil-Malmaison, France
E_mail: chaohao.mse at gmail.com
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