Dear Davide,
I am studying several Cu(II)-based systems. One of them is Cu-L-alanine. Crystallographic unit cell of this complex comprises two Cu atoms and four L-alanine molecules. Hyperfine coupling constants on 13C nuclei calculated by QE-GIPAW were comparable to hyperfine coupling constants calculated by Orca, where the structural model used in Orca consisted of only one Cu atom and two L-alanine molecules. The next system was one of metal-organic frameworks. Its unit cell, supplied to QE-GIPAW calculations, contained 12 Cu atoms, whereas the model used with Orca comprised 6 Cu atoms. The latter structural model described the same motif as was the one contained in the unit cell of periodic calculations. Nevertheless, hyperfine coupling constants on 13C nuclei obtained with QE-GIPAW were about 9-times as large as hyperfine coupling constants obtained with Orca: Orca : QE-GIPAW -0.9 : -7.9 2.4 : 21.0 0.3 : 3.3 For another MOF system again a large factor was between the QE-GIPAW and Orca calculated constants. Best regards Gregor ________________________________ From: users <users-boun...@lists.quantum-espresso.org> on behalf of Davide Ceresoli <davide.ceres...@cnr.it> Sent: Friday, December 18, 2020 12:44:29 PM To: users@lists.quantum-espresso.org Subject: Re: [QE-users] definition of the hyperfine coupling constant in QE-GIPAW Dear Gregor, the hyperfine coupling should be multiplied by the number of unpaired electrons (2*S_z). It also assumes I=1/2. In the past I checked that GIPAW yields the same results of ORCA and Gaussian for molecules in the case S = I = 1/2. I can re-check that. Best. Davide On 12/18/20 10:22 AM, Gregor Mali wrote: > Hello. > > > Isotropic hyperfine coupling constants A_iso, calculated by QE-GIPAW, can > differ > by a large factor from A_iso, obtained by Orca. The factor depends on the > number > of unpaired electrons in the unit cell (used in QE) and in the cluster model > (used in Orca). In Orca, A_iso is proportional to spin-density at the position > of a nucleus divided by <S_z>. <S_z> is the maximum value of the z component. > What is the definition of A_iso in QE-GIPAW? Is it perhaps proportional > to spin-density multiplied by S(S+1)/<S_z>? > > > Thanks in advance! > > > Gregor Mali > > National Institute of Chemistry > > Ljubljana, Slovenia _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu<http://www.max-centre.eu>) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu) users mailing list users@lists.quantum-espresso.org https://lists.quantum-espresso.org/mailman/listinfo/users