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【求助】Ni的声子计算
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我想计算Ni的声子谱。 第一步，先做了结构优化计算，输入文件如下： # Ni fcc structure with two atoms per unit cell #Ni is a ferromagnatic material #spin definition nsppol 2 nspden 2 spinat 0.0 0.0 4.0 prtdos 1 prtden 1 #Structure optimize optcell 1 ionmov 2 ntime 15 dilatmx 1.05 tolmxf 1.0e-6 ecutsm 0.5 ####################################################### #Common data acell 3*6.65184 rprim 0.0 0.5 0.5 0.5 0.0 0.5 0.5 0.5 0.0 ntypat 1 znucl 28 natom 1 typat 1 xred 0.0 0.0 0.0 ixc 11 occopt 3 tsmear 0.01 nband 10 kptopt 1 ngkpt 8 8 8 nshiftk 4 shiftk 0.5 0.5 0.5 0.5 0.0 0.0 0.0 0.5 0.0 0.0 0.0 0.5 ecut 60.0 tolvrs 1.0d-18 iscf 5 nstep 70 diemac 12 计算得到的结果是：acell=6.73,查阅文献的结果是：6.65. 下面计算声子， 第一步，先做了，GS 计算,输入文件是： # Ni fcc structure with two atoms per unit cell #Ni is a ferromagnatic material #spin definition nsppol 2 nspden 2 spinat 0.0 0.0 4.0 prtdos 1 prtden 1 #Structure optimize #optcell 1 #ionmov 2 #ntime 15 #dilatmx 1.05 #tolmxf 1.0e-6 ecutsm 0.5 ####################################################### #Common data acell 3*6.65 rprim 0.0 0.5 0.5 0.5 0.0 0.5 0.5 0.5 0.0 ntypat 1 znucl 28 natom 1 typat 1 xred 0.0 0.0 0.0 ixc 11 occopt 3 tsmear 0.01 nband 10 kptopt 1 ngkpt 8 8 8 nshiftk 4 shiftk 0.5 0.5 0.5 0.5 0.0 0.0 0.0 0.5 0.0 0.0 0.0 0.5 ecut 50 tolvrs 1.0d-18 iscf 5 nstep 70 diemac 12 计算得到WFK文件，以上两步计算都没有问题，no warning and no comment. 第二步计算Gamma点的声子。 输入文件如下， # Crystalline Ni : computation of the second drivative of the total energy # #Ni is a ferromagnatic material #spin definition nsppol 2 nspden 2 spinat 0.0 0.0 4.0 #Response-function calculatio, with q=0 rfphon 1 # Will consider phonon-type perturbation rfatpol 1 1 # all the atoms wiil be displaced rfdir 1 1 1 # Along the first reduced coordinate axis nqpt 1 # One wavevector is to be considered qpt 0 0 0 # This wavevector is q=0 (Gamma) kptopt 2 # Automatic generation of k points, taking # into account the time-reversal symmetry only tolvrs 1.0d-8 # SCF stopping criterion iscf 5 # Self-consistent calculation, using algorithm 5 irdwfk 1 # Read the ground-state wavefunctions ######################################################################### #common input variables #Definition of the unit cell acell 3*6.65 rprim 0.0 0.5 0.5 # In lessons 1 and 2, these primitive vectors 0.5 0.0 0.5 # (to be scaled by acell) were 1 0 0 0 1 0 0 0 1 0.5 0.5 0.0 # that is, the default. #Definition of the atom types ntypat 1 # There is only one type of atom znucl 28 # The keyword "znucl" refers to the atomic number of the # possible type(s) of atom. The pseudopotential(s) # mentioned in the "files" file must correspond # to the type(s) of atom. Here, the only type is Silicon. #Definition of the atoms natom 1 # There are two atoms typat 1 # They both are of type 1, that is, Silicon. xred # This keyword indicate that the location of the atoms # will follow, one triplet of number for each atom 0.0 0.0 0.0 # Triplet giving the REDUCED coordinate of atom 1. # Triplet giving the REDUCED coordinate of atom 2. # Note the use of fractions (remember the limited # interpreter capabilities of ABINIT) #Definition of the planewave basis set ecut 50.0 # Maximal kinetic energy cut-off, in Hartree #Definition of the k-point grid ngkpt 8 8 8 # This is a 8x8x8 grid based on the primitive vectors nshiftk 4 # of the reciprocal space (that form a BCC lattice !), # repeated four times, with different shifts : shiftk 0.5 0.5 0.5 0.5 0.0 0.0 0.0 0.5 0.0 0.0 0.0 0.5 # In cartesian coordinates, this grid is simple cubic, and # actually corresponds to the # so-called 4x4x4 Monkhorst-Pack grid ixc 11 occopt 3 tsmear 0.05 nband 10 #Definition of the SCF procedure nstep 80 # Maximal number of SCF cycles diemac 12.0 # Although this is not mandatory, it is worth to # precondition the SCF cycle. The model dielectric # function used as the standard preconditioner # is described in the "dielng" input variable section. # Here, we follow the prescription for bulk silicon. 问题就来了，得不到合理的结果， 而且log中有一大堆这样的WARNING: cgwf3.F90:701:WARNING New trial energy at line 4 = -8.174248E+02 is higher than former: -8.174248E+02 得到Gamma点声子竟然为： Phonon wavevector (reduced coordinates) : 0.00000 0.00000 0.00000 Phonon energies in Hartree : -3.212615E-03 -3.212615E-03 -3.212615E-03 Phonon frequencies in cm-1 : - -7.050876E+02 -7.050876E+02 -7.050876E+02 有哪位达人能够帮我啊？告诉我问题出在哪里？ 计算中所使用的赝势，可以在这里下载： http://www.sas.upenn.edu/rappegroup/htd ... p_gga.html |
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