Dear Paolo, Thank you for this answer, I should conclude that the small inequalities with respect to the inversion of indices is due convergeance inaccuracy that "emerge naturally" with the filling by irreductible representations. However, if the exchange of indices belongs to the second category, that means that all the components of the dynamical matrix are calculated if I impose nosym=.TRUE.! This seems quite illogical to calculate two times the same thing: only the upper triangular part of the matrix is needed and the lower is symmetric, the inversion of indices should should belong to the first category... Do I say something wrong?
Regards, Antoine Jay On Thursday, October 18, 2018 10:25 CEST, Paolo Giannozzi <[email protected]> wrote: Not sure about this specific case, but only some of the symmetries of the dynamical matrix are enforced in the calculation (in particular: symmetries wrt operations of the small group of q). Other symmetries are not enforced and should "emerge naturally" from the calculation. If I remember correctly, the symmetry of dynamical matrix with respect to exchange of indices belongs to the second category. Another famous example is the acoustic sum rule. In the subsequent processing by auxiliary codes (dynmat, q2r, matdyn) that symmetry is explicitly imposed. Incomplete scf convergence, for instance, may lead to a small loss of symmetry. On Tue, Oct 16, 2018 at 5:11 PM JAY Antoine <[email protected]> wrote:Dear all, I'am trying to understand the symmetries of the dynamical matrix given in the phonon output : Dynamical Matrix in cartesian axes q = ( 0.000000000 0.000000000 0.000000000 ) 1 1 0.26846543 0.00000000 -0.00021832 0.00000000 -0.00074984 0.00000000 -0.00021197 0.00000000 0.26867942 0.00000000 -0.00021197 0.00000000 -0.00074984 0.00000000 -0.00021832 0.00000000 0.26846543 0.00000000 [...] which has the form: A B C D E D C B F Here 6 values A,B,C,D,E and F have been calculated whereas the 3 other force constants have been filled due to the crystal symmetry operations. But what I do not understand is why is this dynamical matrix not symmetric? in the subroutine write_dyn_mat, when phi(i,j,na,nb) is written, its definition is: 1/sqrt(Mna*Mnb)* d^2E/dxadxb d^2E/dxadyb d^2E/dxadzb d^2E/dyadxb d^2E/dyadyb d^2E/dyadzb d^2E/dzadxb d^2E/dzadyb d^2E/dzadzb Due to the Schwarz theorem in the case where na=nb, d^2E/dxadya = d^2E/dyadxa, so in addition to the crystal symmetry operations, the algorithm should fill exactelly D=b with only one calcul. However, it seems that two calculs have been performed in this case giving slighly different values... Another example is given here 1 2 -0.06563923 0.00000000 -0.04490934 0.00000000 -0.04404086 0.00000000 -0.04493368 0.00000000 -0.06590828 0.00000000 -0.04493368 0.00000000 -0.04404086 0.00000000 -0.04490934 0.00000000 -0.06563923 0.00000000 [...] 2 1 -0.06528947 0.00000000 -0.04495765 0.00000000 -0.04411243 0.00000000 -0.04490286 0.00000000 -0.06585596 0.00000000 -0.04490286 0.00000000 -0.04411243 0.00000000 -0.04495765 0.00000000 -0.06528947 0.00000000 I was expecting d^2E/dx1dx2 = d^2E/dx1dx2 and so on... but two calculs have been done and -0.06563923 .neq. -0.06528947! What I am missing there? System is a simple vacancy in a supercell of 215 silicon atoms (ibrav=1), QE V6.0, input given bellow Regards, Antoine Jay LAAS-CNRS, Toulouse France scf.in: &control calculation = 'scf' prefix = 'Si_1V_D2d', tstress = .true. tprnfor = .true. pseudo_dir = '/pseudo/', outdir = 'tmp_Si_1V_D2d/', etot_conv_thr=1.0d-6 forc_conv_thr=1.0d-4 nstep=1400 / &system ibrav = 1, celldm(1) = 30.613571, celldm(2) = 1 , celldm(3) = 1 , nat = 215, ntyp = 1, ecutwfc = 20.0, / &electrons diagonalization='david' mixing_beta = 0.7, conv_thr = 1.0d-9, electron_maxstep=800, / ATOMIC_SPECIES Si 28.086 Si.pz-vbc.UPF ATOMIC_POSITIONS {crystal} Si 0.000162336 0.00014327 0.000162336 Si 0.08330307 0.084189225 0.08330307 Si 0.166992459 0.16800145 0.00058752 Si 0.250912336 0.250721016 0.084924085 Si 0.166156275 -0.000106871 0.166156275 Si 0.249895433 0.082528066 0.249895433 Si 0.00058752 0.16800145 0.166992459 Si 0.084924085 0.250721016 0.250912336 Si 0.333438217 0.001346258 -0.00050172 Si 0.417071186 0.084081282 0.083872754 Si 0.499961127 0.168420495 0.001124771 Si 0.582907731 0.251646989 0.085458254 Si 0.500336958 -0.000934751 0.16550848 Si 0.584924657 0.08068021 0.248592644 Si 0.333277507 0.16668747 0.168141141 Si 0.417190875 0.24867044 0.25351339 Si 0.001507258 0.333858164 0.001507258 Si 0.086913471 0.416162509 0.086913471 Si 0.167357425 0.499603001 0.000978135 Si 0.250615274 0.581869305 0.085464282 Si 0.173265996 0.334321177 0.173265996 Si 0.262140675 0.414034508 0.262140675 Si 0.000978135 0.499603001 0.167357425 Si 0.085464282 0.581869305 0.250615274 Si -0.00050172 0.001346258 0.333438217 Si 0.083872754 0.084081282 0.417071186 Si 0.168141141 0.16668747 0.333277507 Si 0.25351339 0.24867044 0.417190875 Si 0.16550848 -0.000934751 0.500336958 Si 0.248592644 0.08068021 0.584924657 Si 0.001124771 0.168420495 0.499961127 Si 0.085458254 0.251646989 0.582907731 Si 0.333739196 0.333959699 0.000861911 Si 0.41676146 0.41675827 0.085292632 Si 0.499782156 0.49955788 0.000861393 Si 0.582608779 0.582796164 0.08492405 Si 0.498891265 0.334010796 0.1706163 Si 0.571385857 0.419481169 0.262134574 Si 0.334633728 0.499504498 0.170620451 Si 0.416333375 0.584843238 0.253519495 Si 0.000861911 0.333959699 0.333739196 Si 0.085292632 0.41675827 0.41676146 Si 0.170620451 0.499504498 0.334633728 Si 0.253519495 0.584843238 0.416333375 Si 0.1706163 0.334010796 0.498891265 Si 0.262134574 0.419481169 0.571385857 Si 0.000861393 0.49955788 0.499782156 Si 0.08492405 0.582796164 0.582608779 Si 0.333252803 -0.000634212 0.333252803 Si 0.416757556 0.082106584 0.416757556 Si 0.501660471 0.162612654 0.331855779 Si 0.579997453 0.248677535 0.416324449 Si 0.500263622 -0.000631436 0.500263622 Si 0.583620108 0.082532896 0.583620108 Si 0.331855779 0.162612654 0.501660471 Si 0.416324449 0.248677535 0.579997453 Si 0.353262454 0.332627539 0.353262454 Si 0.48026794 0.50088329 0.353261474 Si 0.580006233 0.584849814 0.417191231 Si 0.480248976 0.332642526 0.480248976 Si 0.57137893 0.414042102 0.57137893 Si 0.353261474 0.50088329 0.48026794 Si 0.417191231 0.584849814 0.580006233 Si 0.666669731 0.000706126 -0.000324041 Si 0.750211648 0.083796546 0.083305974 Si 0.833567118 0.167199862 -0.000050503 Si 0.91655396 0.25086993 0.083680781 Si 0.833842252 0.000705685 0.166847757 Si 0.916324599 0.085133815 0.250271264 Si 0.666672794 0.166950385 0.166844061 Si 0.748059434 0.251645742 0.25061009 Si -0.000046498 0.666319325 -0.000046498 Si 0.083310474 0.749720003 0.083310474 Si 0.166849408 0.832812125 -0.000320241 Si 0.249894392 0.917536984 0.082138295 Si 0.166849157 0.666565814 0.166849157 Si 0.248598161 0.752834182 0.248598161 Si -0.000320241 0.832812125 0.166849408 Si 0.082138295 0.917536984 0.249894392 Si -0.000324041 0.000706126 0.666669731 Si 0.083305974 0.083796546 0.750211648 Si 0.166844061 0.166950385 0.666672794 Si 0.25061009 0.251645742 0.748059434 Si 0.166847757 0.000705685 0.833842252 Si 0.250271264 0.085133815 0.916324599 Si -0.000050503 0.167199862 0.833567118 Si 0.083680781 0.25086993 0.91655396 Si 0.666164587 0.333916048 0.000974095 Si 0.746609413 0.417355424 0.086910427 Si 0.832014611 0.49966197 0.001506917 Si 0.916968097 0.582647815 0.083683525 Si 0.832544541 0.333914793 0.167354433 Si 0.916760745 0.416758396 0.25046003 Si 0.660258462 0.499196553 0.173262847 Si 0.748597694 0.582797353 0.2509117 Si 0.668009708 -0.000933789 0.333180451 Si 0.749641931 0.084085043 0.41644676 Si 0.832393129 0.168419579 0.33355623 Si 0.91675807 0.251006558 0.416759205 Si 0.834019246 0.001350301 0.500079104 Si 0.91719377 0.085135734 0.583246733 Si 0.665371779 0.166694627 0.500237846 Si 0.748591761 0.250725201 0.582604154 Si 0.333559034 0.66509661 0.001128602 Si 0.416449984 0.749435486 0.083874863 Si 0.50008047 0.832171776 -0.000502798 Si 0.583626239 0.915979758 0.082135755 Si 0.500243592 0.666827982 0.168143444 Si 0.583625099 0.750989296 0.249896054 Si 0.333183009 0.834450054 0.165510985 Si 0.416760069 0.916758439 0.249516138 Si 0.001128602 0.66509661 0.333559034 Si 0.083874863 0.749435486 0.416449984 Si 0.165510985 0.834450054 0.333183009 Si 0.249516138 0.916758439 0.416760069 Si 0.168143444 0.666827982 0.500243592 Si 0.249896054 0.750989296 0.583625099 Si -0.000502798 0.832171776 0.50008047 Si 0.082135755 0.915979758 0.583626239 Si 0.000974095 0.333916048 0.666164587 Si 0.086910427 0.417355424 0.746609413 Si 0.173262847 0.499196553 0.660258462 Si 0.2509117 0.582797353 0.748597694 Si 0.167354433 0.333914793 0.832544541 Si 0.25046003 0.416758396 0.916760745 Si 0.001506917 0.49966197 0.832014611 Si 0.083683525 0.582647815 0.916968097 Si 0.333180451 -0.000933789 0.668009708 Si 0.41644676 0.084085043 0.749641931 Si 0.500237846 0.166694627 0.665371779 Si 0.582604154 0.250725201 0.748591761 Si 0.500079104 0.001350301 0.834019246 Si 0.583246733 0.085135734 0.91719377 Si 0.33355623 0.168419579 0.832393129 Si 0.416759205 0.251006558 0.91675807 Si 0.66290372 0.334011565 0.334627374 Si 0.748225544 0.416761348 0.416758187 Si 0.832659302 0.499558247 0.333738078 Si 0.916760139 0.582512335 0.416760604 Si 0.832656476 0.333962688 0.499779238 Si 0.916758081 0.416760103 0.583059854 Si 0.662903816 0.499510524 0.498889939 Si 0.748059644 0.581874995 0.582908128 Si 0.331862275 0.670901493 0.331862275 Si 0.41676139 0.751413603 0.41676139 Si 0.500266765 0.834151423 0.333253539 Si 0.584002636 0.916760833 0.416758952 Si 0.501662794 0.670907012 0.501662794 Si 0.584925566 0.752840906 0.584925566 Si 0.333253539 0.834151423 0.500266765 Si 0.416758952 0.916760833 0.584002636 Si 0.334627374 0.334011565 0.66290372 Si 0.416758187 0.416761348 0.748225544 Si 0.498889939 0.499510524 0.662903816 Si 0.582908128 0.581874995 0.748059644 Si 0.499779238 0.333962688 0.832656476 Si 0.583059854 0.416760103 0.916758081 Si 0.333738078 0.499558247 0.832659302 Si 0.416760604 0.582512335 0.916760139 Si 0.666526427 0.66551749 0.000586888 Si 0.750217128 0.749327852 0.083303101 Si 0.833356432 0.833375286 0.000162424 Si 0.916760578 0.916758078 0.083567138 Si 0.832934733 0.665517797 0.166993386 Si 0.917198881 0.748383414 0.250273119 Si 0.667363941 0.833624266 0.166155641 Si 0.751383807 0.915979925 0.249892713 Si 0.667360273 -0.000101737 0.667360273 Si 0.750213428 0.084193206 0.750213428 Si 0.832928801 0.168004203 0.666523002 Si 0.916963111 0.250870651 0.749835955 Si 0.833354131 0.000146272 0.833354131 Si 0.916758642 0.083504699 0.916758642 Si 0.666523002 0.168004203 0.832928801 Si 0.749835955 0.250870651 0.916963111 Si 0.000586888 0.66551749 0.666526427 Si 0.083303101 0.749327852 0.750217128 Si 0.166155641 0.833624266 0.667363941 Si 0.249892713 0.915979925 0.751383807 Si 0.166993386 0.665517797 0.832934733 Si 0.250273119 0.748383414 0.917198881 Si 0.000162424 0.833375286 0.833356432 Si 0.083567138 0.916758078 0.916760578 Si 0.665380336 0.666831005 0.333277607 Si 0.749646639 0.749439394 0.417071213 Si 0.834023558 0.832171881 0.333437911 Si 0.91675889 0.916760845 0.416759799 Si 0.832393772 0.665100367 0.49996154 Si 0.916323235 0.748385702 0.583248032 Si 0.668009949 0.834455299 0.500337021 Si 0.751381555 0.917542097 0.583625291 Si 0.660252589 0.334326299 0.660252589 Si 0.746606463 0.416165083 0.746606463 Si 0.832543349 0.499605526 0.66616452 Si 0.916554188 0.582648947 0.749838499 Si 0.832011417 0.333858507 0.832011417 Si 0.916759573 0.416758985 0.916759573 Si 0.66616452 0.499605526 0.832543349 Si 0.749838499 0.582648947 0.916554188 Si 0.333277607 0.666831005 0.665380336 Si 0.417071213 0.749439394 0.749646639 Si 0.500337021 0.834455299 0.668009949 Si 0.583625291 0.917542097 0.751381555 Si 0.49996154 0.665100367 0.832393772 Si 0.583248032 0.748385702 0.916323235 Si 0.333437911 0.832171881 0.834023558 Si 0.416759799 0.916760845 0.91675889 Si 0.666673889 0.666571113 0.666673889 Si 0.750212344 0.749724309 0.750212344 Si 0.833840442 0.832815634 0.666669721 Si 0.916758455 0.91676045 0.749952566 Si 0.833568833 0.666321048 0.833568833 Si 0.916761377 0.750013726 0.916761377 Si 0.666669721 0.832815634 0.833840442 Si 0.749952566 0.91676045 0.916758455 K_POINTS {automatic} 1 1 1 0 0 0 ph.in: phonon of Si_1V_D2d &inputph tr2_ph=1.0d-14, prefix='Si_1V_D2d', amass(1)=28.0855, outdir='tmp_Si_1V_D2d/' fildyn='Si_1V_D2d.dyn1', fildrho='Si_1V_D2d.drho', / 0.0 0.0 0.0 _______________________________________________ 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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