Dear PWscf users, I am in the process of doing some LDA+U calculations on binary systems, and discovered a peculiar behaviour with Ru-based binary systems. I have been using the PAW pseudopotential Ru.pbe-spn-kjpaw_psl.0.3.0.UPF - it is not in the standard set, but available from THEOS under the PSEUDOPOTENTIALS_TOT/ directory. Aside from the fact that CG style diagonalization suffers (as seen from many iterations where eigenvalues are not converged), the bizarre result is seen in the absolute magnetization.
TYPICAL INPUT FILE: &CONTROL title = "single-point calculation" calculation = 'scf' prefix = "fcc-RuAl" pseudo_dir = "~/mypseudo/" wf_collect=.true. / &SYSTEM ibrav = 0 nat = 4 ntyp = 3 ecutwfc = 80 occupations = 'smearing' smearing = 'methfessel-paxton' degauss = 0.01 nspin = 2 starting_magnetization(1) = 0.1,0.1,0.01 lda_plus_U=.true. Hubbard_U(1)=1D-40,Hubbard_alpha(1)=1D-40 Hubbard_U(2)=1D-40,Hubbard_alpha(2)=1D-40 Hubbard_U(3)=1D-40,Hubbard_alpha(3)=1D-40 nosym_evc=.true. / &ELECTRONS startingwfc='atomic+random' startingpot='atomic' conv_thr = 1.D-6 mixing_beta = 0.5D0 electron_maxstep = 4000 diagonalization = 'cg' / ATOMIC_SPECIES Ru1 101.07 Ru.pbe-spn-kjpaw_psl.0.3.0.UPF Ru2 101.07 Ru.pbe-spn-kjpaw_psl.0.3.0.UPF Al1 26.982 Al.pbe-n-kjpaw_psl.0.1.UPF ATOMIC_POSITIONS (crystal) Al1 0.0 0.0 0.0 Ru1 0.0 0.5 0.5 Al1 0.5 0.0 0.5 Ru2 0.5 0.5 0.0 K_POINTS (automatic) 9 9 9 0 0 0 CELL_PARAMETERS (angstrom) 3.6 0.0 0.0 0.0 3.6 0.0 0.0 0.0 3.6 TYPICAL OUTPUT: .... Iteration #3: Magnetic moment per site: atom: 1 charge: 1.5011 magn: 0.0183 constr: 0.0000 atom: 2 charge: 14.3856 magn: 0.4645 constr: 0.0000 atom: 3 charge: 1.4893 magn: 0.0330 constr: 0.0000 atom: 4 charge: 14.4619 magn: 0.4294 constr: 0.0000 total cpu time spent up to now is 618.8 secs total energy = -5726.20306650 Ry Harris-Foulkes estimate = -4814.95640865 Ry estimated scf accuracy < 25264.02550193 Ry total magnetization = 0.11 Bohr mag/cell absolute magnetization = 2115.04 Bohr mag/cell Iteration #4: Magnetic moment per site: atom: 1 charge: 1.5539 magn: -0.0043 constr: 0.0000 atom: 2 charge: 14.7995 magn: 0.3472 constr: 0.0000 atom: 3 charge: 1.5631 magn: 0.0130 constr: 0.0000 atom: 4 charge: 14.1133 magn: 0.2910 constr: 0.0000 total cpu time spent up to now is 847.5 secs total energy = -6800.82522725 Ry Harris-Foulkes estimate = -5911.29292705 Ry estimated scf accuracy < 12707.95018218 Ry total magnetization = -0.07 Bohr mag/cell absolute magnetization = 1617.61 Bohr mag/cell .... iteration #113 ecut= 80.00 Ry beta=0.50 CG style diagonalization c_bands: 1 eigenvalues not converged c_bands: 1 eigenvalues not converged ethr = 1.00E-02, avg # of iterations = 3.1 negative rho (up, down): 8.618E+02 8.613E+02 Magnetic moment per site: atom: 1 charge: 1.2423 magn: -0.0288 constr: 0.0000 atom: 2 charge: 15.6339 magn: -0.0550 constr: 0.0000 atom: 3 charge: 1.3867 magn: -0.0177 constr: 0.0000 atom: 4 charge: 15.5383 magn: -0.0419 constr: 0.0000 total cpu time spent up to now is 10453.0 secs total energy = -8411.78286402 Ry Harris-Foulkes estimate = -8410.36053542 Ry estimated scf accuracy < 28.63071702 Ry total magnetization = -0.20 Bohr mag/cell absolute magnetization = 144.41 Bohr mag/cell iteration #114 ecut= 80.00 Ry beta=0.50 CG style diagonalization c_bands: 1 eigenvalues not converged ethr = 1.00E-02, avg # of iterations = 3.0 negative rho (up, down): 8.618E+02 8.614E+02 Magnetic moment per site: atom: 1 charge: 1.2416 magn: -0.0288 constr: 0.0000 atom: 2 charge: 15.6333 magn: -0.0558 constr: 0.0000 atom: 3 charge: 1.3864 magn: -0.0179 constr: 0.0000 atom: 4 charge: 15.5402 magn: -0.0446 constr: 0.0000 total cpu time spent up to now is 10529.2 secs total energy = -8411.31255477 Ry Harris-Foulkes estimate = -8411.86059006 Ry estimated scf accuracy < 24.75641734 Ry total magnetization = -0.20 Bohr mag/cell absolute magnetization = 142.71 Bohr mag/cell At this stage I terminated the program. I would expect that both total magnetization and absolute magnetization go to zero, but instead large absolute magnetizations are maintained. Although I could do the calculation without spin, I want the code to find the nonmagnetic state - so far without much luck. Any advice would be highly appreciated! Regards, Jan-Albert NOTICE: Please note that this eMail, and the contents thereof, is subject to the standard Sasol eMail legal notice which may be found at: http://www.sasol.com/legalnotices If you cannot access the legal notice through the URL attached and you wish to receive a copy thereof please send an eMail to legalnot...@sasol.com
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