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Calculating the induced current

Paratec computes the induced current and uses it to calculate the magnetic susceptibility CHI. It is possible to obtain the current directly or from CHI. For a complete basis set the two currents will be identical (see appendix of GMC for details) in practice the two differ very slightly (most likely more due to the n on-local pseudopotential than the basis set). For completness it is possible for paratec to plot out the current dervived from either method. I (jry) recommend obtaining the current from CHI, though you should probably check it agrees with the direct method. A the moment there is a problem with current calculated with the eqn3 and eqn8 methods. This will be fixed soon.

Obtaining the current from CHI
During pw_jobs nmr_shift the magnetic susceptibility is written to a file CHI. During pw_jobs nmr_plot CHI is reread and the induced current calculated. For plotting perposes the magnetic field is 1Tesla in the direction of ket eg ket 0 0 1 . Plots along a line or plane can be defined see section 5.10. As the default the current will be plotted as a 3 component vector. To plot the projection of the current on the direction bra set output_flags_curproj and, for example bra 1 0 0.

Obtaining the current directly
By setting output_flags_current the file JGS is written during pw_jobs nmr_shift. If output_flags_current is present during pw_jobs nmr_plot plots can be made as in the previous section. (This is only implemented for the crystal method, only trivial modifications are needed to make it work in eqn3 and eqn8)


next up previous contents
Next: NMR shift Up: NMR shift Previous: Running NMR jobs   Contents
Jonathan Yates 2001-05-10