On Tue, 29 Sep 2009, Davide Ceresoli wrote: > > 3) lastly, Is it possible to calculate the NMR shift for the > > paramagnetic system using PWSCF? > > (maybe, spin-polarized calculations for the NMR shift.) > The GIPAW code (which does linear response), should work > also for spin polarized systems (magnetic insulators). > I've never tried though...
Unlike NMR chemical shifts of closed-shell systems, chemical shift in paramagnetic species is a statistical (rather than a response) property. Generally speaking, you need to know all spin-Hamiltonian parameters to calculate it - the shielding tensor, the hyperfine tensor, the g-tensor, and (if you radical sites are of a spin higher than 1/2) the zero-field splitting parameters. You may also need to know the spin-spin and spin-lattice relaxation times, or at least have an idea as to their magnitude relative to the NMR time scale. You'll get a better idea of what's involved in such calculation from our (by now slightly dated, but still basically OK) review: S. Moon and S. Patchkovskii, "First-Principles Calculations of Paramagnetic NMR Shifts", pp. 325-338, in M. Kaupp, M. Buehl, and V.G. Malkin (eds), "Calculation of NMR and EPR Parameters", Wiley-VCH, 2004. For the simplest possible case (isolates spin-1/2 paramagnetic centres, relaxing rapidly on the NMR time scale) you may be able to get everything you need from GIPAW - but a fair bit of a bit of coaxing and head-scratching is likely to be involved ... Have fun, Serguei --- Dr. Serguei Patchkovskii Tel: +1-(613)-990-0945 Fax: +1-(613)-947-2838 Skype: Serguei.Patchkovskii E-mail: Serguei.Patchkovskii at nrc.ca Coordinator of Modelling Software Theory and Computation Group Steacie Institute for Molecular Sciences National Research Council Canada Room 2011, 100 Sussex Drive Ottawa, Ontario K1A 0R6 Canada
