[QE-users] Why the choice of different spin orientations leads to completely the same total energy

Jibiao Li jibiaoli at foxmail.com
Mon Apr 26 13:11:27 CEST 2021


Dear All,


I am performing QE calculations by controlling the magnetic state using the keyword" starting_magnetization(1)". The systems that I am studying are Fe-N4 embedded graphene with adsorbed atoms (e.g. Cl, B, F, H, N,P). For each system, I found the total energy is always the same whatever -1 or 1 was used for this option.  



Up: Final energy=-1074.7364064258 Ry, total magnetization=1.99 Bohr mag/cell
Dw: Final energy=-1074.7364064357 Ry, total magnetization=-1.99 Bohr mag/cell


Actually, I am new to magnetism, and just can not understand why the choice of different spin orientations leads to completely the same total energy. Can anyone tell me what's wrong with my calculations? or Should we accept the fact that controlling the spin orientations does not affect the total energy ? Is this a common sense in physics?



 &CONTROL
                 calculation = 'relax' ,
                restart_mode = 'from_scratch' ,
                      outdir = './' ,
                  pseudo_dir = '/home/jibiaoli/pseudo/' ,
                      prefix = '2d' ,
                       nstep = 199 ,
 /
 &SYSTEM
                       ibrav = 8,
                   celldm(1) = 23.59760901,
                   celldm(2) = 0.592429525,
                   celldm(3) = 1.5817524,
                         nat = 36,
                        ntyp = 4,
                     ecutwfc = 49 ,
                     ecutrho = 511 ,
                 occupations = 'smearing' ,
                     degauss = 0.04D0 ,
                    smearing = 'gaussian' ,
                       nspin = 2,
   constrained_magnetization = 'atomic',
   starting_magnetization(1) = 1,
   starting_magnetization(2) = 0,
   starting_magnetization(3) = 0,
   starting_magnetization(4) = 0,
 /
 &ELECTRONS
            electron_maxstep = 299,
                 mixing_beta = 0.2D0 ,
             diagonalization = 'david' ,
 /
 &IONS
                ion_dynamics = 'bfgs' ,
 /
ATOMIC_SPECIES
   Fe   55.850  Fe.pbe-spn-kjpaw_psl.1.0.0.UPF
    N   14.007  N.pbe-n-kjpaw_psl.1.0.0.UPF
    C   12.010  C.pbe-n-kjpaw_psl.1.0.0.UPF
   Cl   35.453  Cl.pbe-n-kjpaw_psl.1.0.0.UPF
ATOMIC_POSITIONS angstrom
Cl            6.9340166756        3.6989245228        2.6428176290
Fe            6.9340166756        3.6989245228        0.8728176290  
N             5.6059434603        2.4072809825        0.8730142439
N             5.6059434603        4.9905680641        0.8730142439
N             8.2619454617        2.4072286380        0.8730110298
N             8.2619454617        4.9906204086        0.8730110298
C            -0.0178633308        0.0000000000        0.8730568507
C            -0.0178354701        2.4770183342        0.8730574443
C            -0.0178354701        4.9208307125        0.8730574443
C             2.0828914672        1.2436366562        0.8730559742
C             2.1294070947        3.6989245238        0.8730543580
C             2.0828914672        6.1542123905        0.8730559742
C             4.1515598342        0.0000000000        0.8730547888
C             4.2422651536        2.4525822834        0.8730507905
C             4.2422651536        4.9452667633        0.8730507905
C             6.2369236427        1.2005616382        0.8730586550
C             6.2369236427        6.1972874084        0.8730586550
C             8.3173386913        0.0000000000        0.8730685226
C            10.3713556874        1.2412551379        0.8730644966
C            10.3159798880        3.6989245238        0.8730564313
C            10.3713556874        6.1565939088        0.8730644966
C             1.3983816512        0.0000000000        0.8730550420
C             1.3982497647        2.4770211151        0.8730548598
C             1.3982497647        4.9208279316        0.8730548598
C             3.4964768966        1.2412907830        0.8730582823
C             3.5518074884        3.6989245238        0.8730504409
C             3.4964768966        6.1565582637        0.8730582823
C             5.5504587549        0.0000000000        0.8730644983
C             7.6308954080        1.2005515154        0.8730595405
C             7.6308954080        6.1972975312        0.8730595405
C             9.7162145171        0.0000000000        0.8730613644
C             9.6256116280        2.4525476568        0.8730541166
C             9.6256116280        4.9453013898        0.8730541166
C            11.7849236132        1.2436057457        0.8730599352
C            11.7383344691        3.6989245238        0.8730590021
C            11.7849236132        6.1542433010        0.8730599352
K_POINTS automatic 
  1 2 1   0 0 0 



 &CONTROL
                 calculation = 'relax' ,
                restart_mode = 'from_scratch' ,
                      outdir = './' ,
                  pseudo_dir = '/home/jibiaoli/pseudo/' ,
                      prefix = '2d' ,
                       nstep = 199 ,
 /
 &SYSTEM
                       ibrav = 8,
                   celldm(1) = 23.59760901,
                   celldm(2) = 0.592429525,
                   celldm(3) = 1.5817524,
                         nat = 36,
                        ntyp = 4,
                     ecutwfc = 49 ,
                     ecutrho = 511 ,
                 occupations = 'smearing' ,
                     degauss = 0.04D0 ,
                    smearing = 'gaussian' ,
                       nspin = 2,
   constrained_magnetization = 'atomic',
   starting_magnetization(1) = -1,
   starting_magnetization(2) = 0,
   starting_magnetization(3) = 0,
   starting_magnetization(4) = 0,
 /
 &ELECTRONS
            electron_maxstep = 299,
                 mixing_beta = 0.2D0 ,
             diagonalization = 'david' ,
 /
 &IONS
                ion_dynamics = 'bfgs' ,
 /
ATOMIC_SPECIES
   Fe   55.850  Fe.pbe-spn-kjpaw_psl.1.0.0.UPF
    N   14.007  N.pbe-n-kjpaw_psl.1.0.0.UPF
    C   12.010  C.pbe-n-kjpaw_psl.1.0.0.UPF
   Cl   35.453  Cl.pbe-n-kjpaw_psl.1.0.0.UPF
ATOMIC_POSITIONS angstrom
Cl            6.9340166756        3.6989245228        2.6428176290
Fe            6.9340166756        3.6989245228        0.8728176290  
N             5.6059434603        2.4072809825        0.8730142439
N             5.6059434603        4.9905680641        0.8730142439
N             8.2619454617        2.4072286380        0.8730110298
N             8.2619454617        4.9906204086        0.8730110298
C            -0.0178633308        0.0000000000        0.8730568507
C            -0.0178354701        2.4770183342        0.8730574443
C            -0.0178354701        4.9208307125        0.8730574443
C             2.0828914672        1.2436366562        0.8730559742
C             2.1294070947        3.6989245238        0.8730543580
C             2.0828914672        6.1542123905        0.8730559742
C             4.1515598342        0.0000000000        0.8730547888
C             4.2422651536        2.4525822834        0.8730507905
C             4.2422651536        4.9452667633        0.8730507905
C             6.2369236427        1.2005616382        0.8730586550
C             6.2369236427        6.1972874084        0.8730586550
C             8.3173386913        0.0000000000        0.8730685226
C            10.3713556874        1.2412551379        0.8730644966
C            10.3159798880        3.6989245238        0.8730564313
C            10.3713556874        6.1565939088        0.8730644966
C             1.3983816512        0.0000000000        0.8730550420
C             1.3982497647        2.4770211151        0.8730548598
C             1.3982497647        4.9208279316        0.8730548598
C             3.4964768966        1.2412907830        0.8730582823
C             3.5518074884        3.6989245238        0.8730504409
C             3.4964768966        6.1565582637        0.8730582823
C             5.5504587549        0.0000000000        0.8730644983
C             7.6308954080        1.2005515154        0.8730595405
C             7.6308954080        6.1972975312        0.8730595405
C             9.7162145171        0.0000000000        0.8730613644
C             9.6256116280        2.4525476568        0.8730541166
C             9.6256116280        4.9453013898        0.8730541166
C            11.7849236132        1.2436057457        0.8730599352
C            11.7383344691        3.6989245238        0.8730590021
C            11.7849236132        6.1542433010        0.8730599352
K_POINTS automatic 
  1 2 1   0 0 0 




Dr. Jibiao Li, 
Department of Material Science and Engineering
Yangtze Normal University
Juxian Dadao 16#, Fuling, Chongqing, China
Email: jibiaoli at yznu.edu.cn, jibiaoli at foxmail.com, jibiao.li at hotmail.com
Homepage: https://www.researchgate.net/profile/Jibiao_Li
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