[QE-users] Why the choice of different spin orientations leads to completely the same total energy
Juan Hernández-Tecorralco
juanht at ifuap.buap.mx
Mon Apr 26 20:11:23 CEST 2021
I think is nothing wrong with your calculation. But you have right,
different spin configurations would give differents values in total
energy. In this case, you get the same total energy because both cases
have the same magnetic configuration but opposite signs.
This occurs because in spin-polarized calculations you need to converge
two densities, "n = n_up + n_dw" and "m = n_up - n_dw". For the same
"n", you can get two "m" values, positive or negative.
I hope to have helped you
On 2021-04-26 06:11, Jibiao Li wrote:
> 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_
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu [1])
> users mailing list users at lists.quantum-espresso.org
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