Unrestricted calculations with PBC in QMCPAC

[Jila3997]

Hi everybody I'm new at QMCPACK. I want to use qmcpack to do QMC calculation on transition metal oxid like NiO by using pyscf to generate input file.

I run the pyscf input file for 1st step. (KUHF calculation method) Now I got an error : Unrestricted calculations with PBC not supported (yet) - contact Developers

I have a 2 questions:

1. How can we define an AFM phase for such materials in qmcpack? Is it implemented in qmcpack or not?

2. I want to use pseudopotental in HF calculation by PySCF, now my question is : Do they use the same PseudoPotential ?

[prckent]

• QMCPACK supports AFM, but some parts of the UHF support for periodic gaussians are not implemented yet. @anbenali might comment if this is just the PySCF converter or there are extra fixes needed.
• The preferred route would be to use a plane wave input starting from e.g. Quantum ESPRESSO. This is fully supported and the trial wavefunction will be faster to evaluate in the QMC. It can also be made more accurate by adding plane waves without affecting the QMC execution time, unlike the Gaussian basis set route.
• We recommend pseudopotentials from https://pseudopotentiallibrary.org
• If you are new to QMC, I advise starting with the tutorials (e.g. https://github.com/QMCPACK/qmc_workshop_2021 ) and e.g. running bulk silicon or graphene to get started. These are cheaper to run and use the same concepts.