NMR options

The following is a brief list of all the paratec options directly related to NMR calculations. Further details are provided below.

• pw_jobs nmr_shift Computes current due to a perturbing magnetic field, the local diamagnetic susceptibility and the chemical shieldings at each nuclear position
• pw_jobs nmr_plot Plots the induced current
• nmr_q 0.001 sets the q (in cartesian coordinates), which determines the periodicity of the applied external field. Default: nmr_q 0.01
• checkpoint nmr The code will checkpoint the NMR shift calculation after each kpoint. You can recover from a crash by giving an input_flags of chkptchi.
• output_flags eg output_flags_crystal_current
  • original Use the original MPL approach for calculating shielding. Do not use this option, it is kept for historical reasons only!
  • crystal Use the approach of PM for calculating the shielding. This is the default option.
  • eqn3 For molecules only. Use the Molecular approach of PM. Refers to equation 3 of GMC.
  • eqn8 For molecules only. Use the Molecular Sum Rule approach of PM. Refers to equation 8 of GMC.
  • current For pw_jobs nmr_shift this writes a file JGS containing the current in g space. For pw_jobs nmr_plot this reads from JGS and does line_plots or slice_plots as described in section 5.10. The magnetic field is in the direction of ket
  • nmrshift To get a plot of the susceptibility (section 5.10).
• input_flags eg input_flags_wavefn_chkptchi
  • chkptchi This causes a restart from a CHKPTCHI file
  • wavefn Use the wavefunctions from a previous scf run as a starting guess for the first diagonalization. Recommended. Essential for a spin polarized calculation.

• optimize_flags eg optimize_flags_memory
  • memory optimizes for memory in the calculation of NMR shifts, at a small expense in additional CPU time.
  • nocgsolveguess switches OFF the better starting guesses for the conjugate gradient solver in the NMR subroutine. Using this option will generally result in SUBSTANTIALLY SLOWER execution, but will reduce memory cost.