# Qgrid for radial form factors of non-local pseudopotential

**URL:** <https://discourse.abinit.org/t/qgrid-for-radial-form-factors-of-non-local-pseudopotential/3773>\
**Category:** Other tools and postprocessing in ABINIT\
**Created:** [October 30, 2025, 8:10pm UTC](https://discourse.abinit.org/t/qgrid-for-radial-form-factors-of-non-local-pseudopotential/3773 "2025-10-30T20:10:56Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![tonyvuu](https://discourse.abinit.org/letter_avatar_proxy/v4/letter/t/e19adc/32.png) [@tonyvuu](https://discourse.abinit.org/u/tonyvuu)\
**Post date:** [October 30, 2025, 8:10pm UTC](https://discourse.abinit.org/t/qgrid-for-radial-form-factors-of-non-local-pseudopotential/3773/1 "2025-10-30T20:10:56Z")

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Hello,

I am trying to reconstruct the non-local part of the pseudopotential to compute some matrix elements. I am using the [PSPS.nc](http://psps.nc/) output file (generated with iomode = 3 and prtpsps = 1) and I have some trouble with the radial form factors specifically. The way I understand it, Abinit stores the cubic spline data (ffspl) and the grid on which they are stored (qgrid\_ff). My issue is that even with a stringent pseudopotential (e.g. the NC SR (ONCVPSP v0.5 PBE stringent psp8 for Carbon from Pseudodojo), the qgrid given by the [PSPS.nc](http://psps.nc/) output file stops at q=3.1416 … I have to evaluate the radial form factors at some |k+G| vectors that are much larger than that, in fact, around 90% of my |k+G| vectors lie outside of qgrid, for an ecut of 40 Ha. I suspect this making my non-part not very good. Am I missing something or is it normal that Abinit tabulates qgrid until 3.14? If that’s the case, do I have to compute the form factors myself on a custom qgrid from the input .psp8 file? I have attached my input file.

Thank you.

Tony Vuu, on behalf of a colleague

[graphene\_p\_uc\_5x5x1.abi](https://discourse.abinit.org/uploads/short-url/brHMsgKxmRjrP2jTVFnWawIBenO.abi) (1.9 KB)