Re: [Pw_forum] Open shell system calculations
I have a single Mn2+ ion in the isolated system with vacuum between periodic images. Spin-unpolarized calculations run without any errors so I wonder whether spin-unpolarized calculations produce any useful results. Best, Iryna Zaporozhets 2017-08-09 23:39 GMT-07:00 stefano de gironcoli : > depends on your system, is it magnetic ? > metallic aluminum or copper have spin compensated densities and you can > use nspin=1. > nickel or iron are magnetic and nspin=2 is needed. > stefano > > > On 10/08/2017 08:29, Iryna Zaporozhets wrote: > > Dear PW community, > > I am working with an open-shell system which requires a lot of > computational efforts. Is it possible to use other options than > spin-polarized calculations (nspin = 2) to reduce computational cost, for > example, restricted open-shell DFT? Is there any physical meaning to the > results obtained with spin-unpolarized (nspin = 1) calculations in case of > the open-shell system? > > Thank you, > Iryna Zaporozhets, > Master student in Chemistry > Kharkiv National University, Ukraine > > > ___ > Pw_forum mailing > listPw_forum@pwscf.orghttp://pwscf.org/mailman/listinfo/pw_forum > > > > ___ > Pw_forum mailing list > Pw_forum@pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
Re: [Pw_forum] Open shell system calculations
depends on your system, is it magnetic ? metallic aluminum or copper have spin compensated densities and you can use nspin=1. nickel or iron are magnetic and nspin=2 is needed. stefano On 10/08/2017 08:29, Iryna Zaporozhets wrote: Dear PW community, I am working with an open-shell system which requires a lot of computational efforts. Is it possible to use other options than spin-polarized calculations (nspin = 2) to reduce computational cost, for example, restricted open-shell DFT? Is there any physical meaning to the results obtained with spin-unpolarized (nspin = 1) calculations in case of the open-shell system? Thank you, Iryna Zaporozhets, Master student in Chemistry Kharkiv National University, Ukraine ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
[Pw_forum] Open shell system calculations
Dear PW community, I am working with an open-shell system which requires a lot of computational efforts. Is it possible to use other options than spin-polarized calculations (nspin = 2) to reduce computational cost, for example, restricted open-shell DFT? Is there any physical meaning to the results obtained with spin-unpolarized (nspin = 1) calculations in case of the open-shell system? Thank you, Iryna Zaporozhets, Master student in Chemistry Kharkiv National University, Ukraine ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
[Pw_forum] about q-path for matdyn calculation
Dear users I am new in Tc-calculation. I am not fully understand how to extract q-path from band structure calculation this I read in some tutorials. that I needed for matdyn calculation. can anyone please give me hint how to calculate. Thank you in advance. surender IIT Kanpur ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
[Pw_forum] Raman Intensity Comparing monolayer MoS2 and monolayer MoTe2
Hi Everyone, I am James Johns from the University of Minnesota Chemistry Department. I was trying to assign the modes in an experimental Raman spectrum by comparison to calculations using symmetry and the predicted off-resonance intensity (the material contains Mo and Te). The intensities that I calculated seemed to be nonsense, so I tried looking at two simpler systems, monolayer MoS2 and monolayer MoTe2. When I calculate the Raman intensities for MoS2, I get reasonable agreement with experiment (two primary peaks, and E1 and A1, with similar intensities (A 2:1 ratio). When I swap to MoTe2, which has a similar first order Raman spectrum (2 peaks, 1 E1 and one A1 with similar intensity) I see that the symmetries are correct, but the A1 mode is much more intense than the E1 pair (816 A^4/amu vs 8 A^4/amu). I thought his might be an issue with the Te pseudopotential, so I tried two others (a Troullier-Martin and a Hartwigsen-Goedeker-Hutter pseudopotential) and while the numbers changed, the pattern didn't. When I try to calculate the Raman intensities for my actual system, I always see a similar trend where one mode is calculated to be vastly more intense than the others. I've copied the output of my dynmat input files and the input files for pw.x, ph.x, and dynmat.x below, but I wanted to ask if anyone had any thoughts on why the LDA MoS2 intensity would be approximately correct, but not MoTe2? Thanks, James Johns MoTe2 Dynmat Output:: # mode [cm-1][THz] IR Raman depol.fact 1 -0.00 -0.0. 5.71000.7500 2 -0.00 -0.0. 5.76620.7500 3 0.000.0. 0.05620.7500 4119.783.59080. 0.53110.7500 5119.783.59080. 0.53110.7500 6174.025.21710. 816.72960.1155 7239.257.17265.0484 8.29780.7500 8239.257.17265.0484 8.29780.7500 9296.368.88460.0096 0.0.1201 MoS2 Dynmat Output: # mode [cm-1][THz] IR Raman depol.fact 1 -0.00 -0.0. 0.46550.7500 2 0.000.0. 0.00260.7500 3 0.000.0. 0.46450.7500 4287.408.61590. 0.20810.7500 5287.408.61590. 0.20810.7500 6390.61 11.71031.453073.69680.7500 7390.61 11.71031.453073.69680.7500 8406.95 12.20000. 461.77320.1076 9474.79 14.23370.0043 0.0.1812 ### ### Input Files for MoS2 PW.X Input &control calculation= 'relax' nstep = 75 etot_conv_thr= 1.0d-7 forc_conv_thr= 1.0d-6 prefix='MoS2.PBE' outdir='/home/johnsj/jjohns/MoS2_Phonon' pseudo_dir='/home/johnsj/jjohns/Psuedo/PSEUDOPOTENTIALS_NC' !tefield=.true., !dipfield=.true., / &system ibrav= 4, celldm(1)=5.95799552 , celldm(3)=14.5844 nat= 3, ntyp=2, nbnd=50, ecutwfc=60.0, occupations='fixed' !smearing='gauss' !degauss=0.01 !vdw_corr= 'ts' !edir=3 !emaxpos = 0.05 !eopreg =0.1 !eamp=0 !nspin=2 !starting_magnetization(2)=0.5 !input_dft='HSE' !nqx1=1, nqx2=1, nqx3=1 / &electrons / &ions / &cell !cell_dofree='2Dxy' / ATOMIC_SPECIES S 32.065 S.pz-n-nc.UPF Mo 95.94 Mo.pz-n-nc.UPF ATOMIC_POSITIONS crystal S 1/3 2/3 0.4642 Mo 2/3 1/3 0.5 S 1/3 2/3 0.5358 K_POINTS automatic 15 15 1 0 0 0 PH.X Input phonons of MoS2 at Gamma &inputph tr2_ph=1.0d-14 prefix='MoS2.PBE' outdir='/home/johnsj/jjohns/MoS2_Phonon' fildyn='MoS2.dynG' lraman=.true. asr=.true. epsil=.true. verbosity='high', / 0.0 0.0 0.0 Dynmat.x Input &input fildyn='MoS2.dynG' asr='crystal' q=0.0 0.0 0.0 filxsf='MoS2.xsf' / # # Input Files for MoTe2 &control calculation= 'relax' nstep = 75 etot_conv_thr= 1.0d-7 forc_conv_thr= 1.0d-6 prefix='MoTe2.PBE' outdir='/home/johnsj/jjohns/MoS2_Phonon' pseudo_dir='/home/johnsj/jjohns/Psuedo/PSEUDOPOTENTIALS_NC' !tefield=.true., !dipfield=.true., / &system ibrav= 4, celldm(1)=6.64030863 , celldm(3)=14.5844 nat= 3, ntyp=2, nbnd=50, ecutwfc=60.0, occupations='fixed' / &electrons / &ions / &cell !cell_dofree='2Dxy' / ATOMIC_SPECIES Te 127.6 Te.pz-n-nc.UPF Mo 95.94 Mo.pz-n-nc.UPF ATOMIC_POSITIONS crystal Te 1/3 2/3 0.4642 Mo 2/3 1/3 0.5 Te 1/3 2/3 0.5358 K_POINTS automatic 15 15 1 0 0 0 PH.X Input phonons of MoTe2 at Gamma &inputph tr2_ph=1.0d-14 prefix='MoTe2.PBE' outdir='/home/johnsj/jjohns/MoS2_Phonon' fildyn='MoTe2.dynG'
Re: [Pw_forum] SCF calculations for molecules in electric fieldsare not converged
Dear Jibiao, If you would like to use modern theory of polarization (MTP) version of applying the electric field and reach 1 Ry a.u., then you can do this gradually. So converge 0.1 a.u., keep the wave functions, and use them as initial guess to 0.2 a.u.. Repeat with steps of 0.1 a.u. until you reach 1 a.u. An alternative would be using a classical saw-tooth potential to apply the field using tefield tag (instead of lelfield). This may be a bit easier to converge. I would experiment with both approaches. The classical saw-tooth implementation allows smearing, whereas MTP implementation does not. But you do not really need smearing for isolated molecules, you can use fixed occupations or even occupations read from input file. See example05 of PW examples. If you, however, insist on applying smearing with MTP, you can comment out the places in the PW/src files where there is an If statement to check that this is an insulator (i.e. fixed occupations) and recompile the code. You need to check this carefully on your own. The key idea is that smearing is sometimes useful with insulators and there is no harm in applying it with MTP as long as the final solution remains an insulator. But at the time when MTP was implemented in PWscf it was thought that smearing immediately implies a metal which is of course problematic for MTP. Again, I do not recommend this option unless you really need it and you make sure that things work consistently. Mostafa ___ Pw_forum mailing list Pw_forum@pwscf.org http://pwscf.org/mailman/listinfo/pw_forum
