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Crystalline nickel †

This tutorial explains how to perform a spin-polarized calculation and how to perform the electronic structure analysis.

SCF calculation †

To calculate a system with spin polarization, one needs to set NSPIN=2 and nonzero initial magnetizatin (ZETA1). With this input file, densities of states projected onto the atomic orbitals (AO_LDOS or PDOS) are printed in the output file.

• Input file (nfinp_scf)

   0  0  0  0  0  0
   5.00  15.00 1   1   1                : GMAX, GMAXP, NTYP, NATM, NATM2
   225   2                              : num_space_group, type
   6.70  6.700  6.700 90.00 90.00 90.00 : a,b,c,alpha,beta,gamma
   16  16  16  1   1   1                : K_mesh
   0   0                                : NCORD, NINV,   : IWEI, IMDTYP, ITYP
   0.00  0.00   0.00  1  0  1           : CPS(1,1:3) IWEI IMDTYP ITYP
   28    0.50   58.69 6  1  0.1         : IATOMN,ALFA,AMION,ILOC,IVAN ZETA1
   0  0  0  0  0                        : ICOND INIPOS INIVEL ININOS INIACC
   0  1                                 : IPRE IPRI
   30 30    0  84200.00  0              : NMD1 NMD2 LAST_ITER CPUMAX IFSTOP
   6  1                                 : WAY_MIX MIX_WHAT
   0  20 0.30                           : ITER_START KBXMIX MIX_ALPHA
   0.20  0.30  0.20  0.20  0.20         : DTIM1 DTIM2 DTIM3 DTIM4 DTIM
   300.00   4  1     0.50D-09           : DTIO IMDALG IEXPL EDELTA
   -10.020  0.50D+03 0                  : WIDTH FORCCR ISTRESS
  ggapbe    2                           : XCTYPE KSPIN
   2.00                                 : DESTM
   102                                  : NBZTYP
   4    4    4                          : NKX NKY NKZ (DUMMY)
   4    4    4                          : NKX2 NKY2 NKZ2 (DUMMY)
   24                                   : KEG
   1                                    : NEXTST
   0                                    : (DUMMY)
   2                                    : IMSD
   0                                    : EVALUATE_EKO_DIFF
   1                                    : NPDOSAO
   1                                    : IPDOST
   -15.00  5.00  0.20   501             : EPDOS(1) EPDOS(2) EPDOS(3) NPDOSE
     2.40  0.20                         : RPDOS(1) RPDOS(2)
     0.20  14                           : DR NR
   0   0.00                             : DUMMY DUMMY

Band structure calculation †

After the SCF calculation, perform a non-SCF band structure calculation by setting ICOND=22 and high-symmetry k-points in the &KPOINTS_BAND...&END block

• nfinp_band

   0  0  0  0  0  0
   5.00  15.00 1   1   1                : GMAX, GMAXP, NTYP, NATM, NATM2
   225   2                              : num_space_group, type
   6.70  6.700  6.700 90.00 90.00 90.00 : a,b,c,alpha,beta,gamma
   16  16  16  1   1   1                : K_mesh
   0   0                                : NCORD, NINV,   : IWEI, IMDTYP, ITYP
   0.00  0.00   0.00  1  0  1           : CPS(1,1:3) IWEI IMDTYP ITYP
   28    0.50   58.69 6  1  0.1         : IATOMN,ALFA,AMION,ILOC,IVAN
   22 0  0  0  0                        : ICOND INIPOS INIVEL ININOS INIACC
   0  1                                 : IPRE IPRI
   30 30    0  84200.00  0              : NMD1 NMD2 LAST_ITER CPUMAX IFSTOP
   6  1                                 : WAY_MIX MIX_WHAT
   0  20 0.30                           : ITER_START KBXMIX MIX_ALPHA
   0.20  0.30  0.20  0.20  0.20         : DTIM1 DTIM2 DTIM3 DTIM4 DTIM
   300.00   4  1     0.50D-09           : DTIO IMDALG IEXPL EDELTA
   -10.020  0.50D+03 0                  : WIDTH FORCCR ISTRESS
  ggapbe    2                           : XCTYPE KSPIN
   2.00                                 : DESTM
   102                                  : NBZTYP
   4    4    4                          : NKX NKY NKZ (DUMMY)
   4    4    4                          : NKX2 NKY2 NKZ2 (DUMMY)
   24                                   : KEG
   1                                    : NEXTST
   0                                    : (DUMMY)
   2                                    : IMSD
   0                                    : EVALUATE_EKO_DIFF
   0                                    : NPDOSAO
   0   0.00                             : DUMMY DUMMY
  &KPOINTS_BAND
   NKSEG 4
   KMESH 40 20 20 20
   KPOINTS
   0.000 0.000 0.000
   0.000 0.500 0.500
   0.250 0.500 0.750
   0.500 0.500 0.500
   0.000 0.000 0.000
  &END

Postprocessing †

To plot the band strcture of a spin polarized system, perfrom the following

> energy2band -s

and input the number of bands, the number of bands used to plot the band, the number of k-points, and the Fermi level. DO NOT forget to add the option "-s", which is necessary for the spin-polarized system. Then one obtain "band_up.data" and "band_dw.data" for spin-up and spin-down states, respectively, which can be used to plot the band structure using gnuplot, xmgrace, or alike. Here is an example of the gnuplot script

set terminal postscript eps 'Helvetica' 22
set output 'band.eps'
emin=-10.0
emax=10.0
xmin=0.0
xmax=2.88194910
G=0.0
X=0.93778885
W=1.40668328
L=2.06980013
G2=2.88194910
offset=0.75
set xrange [xmin:xmax]
set yrange [emin:emax]
set key top left
unset xtics
unset xlabel
set ylabel 'E-E_F (eV)'
set xzeroaxis
set arrow from X,emin to X,emax nohead
set arrow from W,emin to W,emax nohead
set arrow from L,emin to L,emax nohead
set label '{/Symbol G}' at G,emin-offset center
set label 'X' at X,emin-offset center
set label 'W' at W,emin-offset center
set label 'L' at L,emin-offset center
set label '{/Symbol G}' at G2,emin-offset center
plot 'band_up.data' using 1:2  with lines title 'Spin-up' lt 1 lw 3,     'band_dw.data' using 1:2  with lines title 'Spin-down' lt 2 lw 3

Using this script one gets the following band structure of fcc Ni:

The total density of states is written to "dos.data" and can be plotted. Following is an example gnuplot script:

set terminal postscript eps 'Helvetica' 22
set output 'dos.eps'
set xrange [-10:5]
set yrange [-3.5:3.5]
set xzeroaxis lt 1
set yzeroaxis
set key left top
set xlabel 'E-E_F (eV)'
set ylabel 'Density of states (states/eV)'
plot 'dos.data' using ($1):($2) title 'Spin-up' with lines lt 1 lw 2,\
     ''         using ($1):(-$3) title 'Spin-down' with lines lt 2 lw 2

and the resulting figure looks like this: