[Wien] Problems of HCP Tb

Hui Wang hwang at imr.ac.cn
Fri Jan 29 05:12:24 CET 2010


Dear Wien users:
    I am running wien version wien2k 08_03 on a machine of type Xeon with operating system suse linux, fortran compiler ifort 10.1.021 and math libraries mkl 10.0.2.018.
    I have been trying to simulate hcp Tb for weeks, no matter whatever I did (including change the parameters and use different method such as GGA+U or SO), I still couldn't get the right magnetic moment of Tb atom, and the convergence criterion was met. The experimental magnetic moment of Tb is around 10 uB, but the largest magnetic moment I got by wien2k_08.3 was around 7.6 uB (GGA+U+SO).
    My computational details are as follows:
    here are all the import input files are prepared before runsp_lapw:
    case.struct
*************************************************************
HCP_Tb
H   LATTICE,NONEQUIV.ATOMS:  1 194 P63/mmc
MODE OF CALC=RELA unit=bohr
  6.803402  6.803402 10.767485 90.000000 90.000000120.000000
ATOM  -1: X=0.33333333 Y=0.66666667 Z=0.75000000
          MULT= 2          ISPLIT= 4
      -1: X=0.66666667 Y=0.33333333 Z=0.25000000
Tb1        NPT=  781  R0=0.00010000 RMT=   2.50000   Z: 65.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
  24      NUMBER OF SYMMETRY OPERATIONS
*************************************************************
    case.in1
*************************************************************
WFFIL        (WFPRI, SUPWF)
  7.00       12    4 (R-MT*K-MAX; MAX L IN WF, V-NMT
  0.30    6  0      (GLOBAL E-PARAMETER WITH n OTHER CHOICES, global APW/LAPW)
 0    0.30      0.000 CONT 1
 0   -3.53      0.005 STOP 1
 1   -1.70      0.010 CONT 1
 1    0.30      0.000 CONT 1
 3    0.30      0.010 CONT 1
 2    0.30      0.010 CONT 1
K-VECTORS FROM UNIT:4   -15.0       5.0    48   emin/emax/nband
*************************************************************
    case.in2
*************************************************************
TOT             (TOT,FOR,QTL,EFG,FERMI)
      -9.0      38.0 0.50 0.05                EMIN, NE, ESEPERMIN, ESEPER0
TETRA    0.000          (GAUSS,ROOT,TEMP,TETRA,ALL      eval)
  0 0  2 0  3 3  4 0  5 3  6 0  6 6
 12.00          GMAX
NOFILE        FILE/NOFILE  write recprlist
*************************************************************
    case.inm
*************************************************************
MSEC1  0.0   YES  (BROYD/PRATT, extra charge (+1 for additional e), norm)
0.02            mixing FACTOR for BROYD/PRATT scheme
1.00  1.00      PW and CLM-scaling factors
9999  8         idum, HISTORY
*************************************************************
    case.inst
*************************************************************
Tb
Xe 4
4, 3,3.0  N
4, 3,1.0  N
4,-4,4.0  N
4,-4,0.0  N
5, 2,1.0  N
5, 2,0.0  N
6,-1,1.0  N
6,-1,1.0  N
****
****         END of input (instgen_lapw)
*************************************************************
    case.indm
*************************************************************
-15.                      Emin cutoff energy
 1                       number of atoms for which density matrix is calculated
 1  1  3      index of 1st atom, number of L's, L1
 0 0           r-index, (l,s)index
*************************************************************
    case.indmc
*************************************************************
-15.                      Emin cutoff energy
 1                       number of atoms for which density matrix is calculated
 1  1  3      index of 1st atom, number of L's, L1
 0 0           r-index, (l,s)index
*************************************************************
    case.inorb  (here, the value of u varies from 0.0 to 0.7 Ry)
*************************************************************
  1  1  0                     nmod, natorb, ipr
PRATT  1.0                    BROYD/PRATT, mixing
  1 1 3                          iatom nlorb, lorb
  1                              nsic 0..AFM, 1..SIC, 2..HFM
   0.10 0.00        U J (Ry)   Note: we recommend to use U_eff = U-J and J=0
*************************************************************
    case.inso

*************************************************************
WFFIL
 4  1  0                      llmax,ipr,kpot
 -15.0000   5.0000           emin,emax (output energy window)
   0.  0.  1.                 direction of magnetization (lattice vectors)
 1                           number of atoms for which RLO is added
 1   -1.7      0.01       atom number,e-lo,de (case.in1), repeat NX times
 0 0 0 0 0                    number of atoms for which SO is switch off; atoms
*************************************************************
other parameters: RMT = 2.5, Kpoints: 1000, IBZ: 76
*************************************************************
 
Result: 
by GGA+U:
command line: runsp -ec 0.0001 -cc 0.0001 -orb -i 1000
 U(Ry)    E(Ry/cell)     M(uB/atom)
  0.0    -46876.362489    5.86499
  0.1    -46876.362491    5.86434 ( whe Ueff = 0.1 Ry, using -orb doesn't converge, so i use -orbc)
  0.2    -46876.263915    6.20827
  0.3    -46876.270606    6.25566
  0.4    -46876.260620    6.26501
  0.5    -46876.232366    6.26697
  0.6    -46876.243298    6.27250
  0.7    -46876.216162    6.27217
 
by GGA+U+SO (based on the result of GGA+U, and rm *.broy*)
command line: runsp -ec 0.0001 -cc 0.0001 -orb -so -i 1000
U(Ry)    E(Ry/cell)   M_spin(uB/atom)  M_orbit(uB/atom)
0.0     -46876.609319     5.81268     1.25824
0.1     -46876.335016     6.04722     0.00000 (GGA+U+SO doesn't converge, i don't know why ?)
0.2     -46876.507404     6.19715     1.40041
0.3     -46876.498692     6.23715     0.01548
0.4     -46876.487014     6.25003     0.00605
0.5     -46876.470927     6.25129     1.33299
0.6     -46876.467519     6.26165     0.00113
0.7     -46876.452793     6.25998     1.36656
     
     Two questions:
     (1)From the data above, the largest magnetic moment of atom Tb is about 7.6 uB, which is still small than the experimental magnetic moment (10 uB). How can I get the right magnetic moment of Tb?
    (2)About GGA+U, it need case.indm or case.indmc ? runsp -orb or runsp -orbc ?
       About GGA+U+SO, there are two Tb atoms which are at the unequivalent position, how to change the case.inso files ?
       case.inso

*************************************************************
WFFIL
 4  1  0                      llmax,ipr,kpot
 -15.0000   5.0000           emin,emax (output energy window)
   0.  0.  1.                 direction of magnetization (lattice vectors)
 1                        number of atoms for which RLO is added
 1   -1.7      0.01       atom number,e-lo,de (case.in1), repeat NX times ( if i wanna add RLO to the second Tb atom, what should I do ?)
 0 0 0 0 0                    number of atoms for which SO is switch off; atoms
*************************************************************
 
    I know havey rare earth elements are hard to deal with , and I really need someone who can give me some enlightenment. Any suggestion will be greatly appreciated.
    I am looking forward to your reply.
    Cheers.
 
Yours sincerely
Hui Wang


 
 
 

=========================================================
Magnetism and Magnetic Materials Division
Shenyang Materials Science National Laboratory
Institute of Metal Research
Chinese Academy of Sciences
72 Wenhua Road, Shenyang 110016, P. R. China
Tel: +86-24-83978845
PHD: Wanghui
Email: hwang at imr.ac.cn 
========================================================= 

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