Hi,

What is "going wrong" on the very immediate basis is a failure of a Lapack routine, DYSTREF, which is designed to diagonalise a certain type of high-symmetry matrix, and it is happening inside the algorithm designed to precondition the Kohn-Sham states (presumably during density mixing?)

I would also be curious how quickly this occurs -- currently the default for castep is to perform a "quick" guess of the wavefunction at a low cut off, and use this to improve the convergence of the wavefunction. While this is good generally, I have found that sometimes non-collinear systems will converge better if you try

%block devel_code

no_improve_wvfn

%endblock devel_code

in your param file.

Also, if you are running SOC, have you included relativistic_treatment: dirac ?

I would also suggest that the jiscmail mailing list for CASTEP is actively viewed by the developers, who can probably give you a more precise answer! (They would probably want to see both your cell and param files, and where the castep file got to -- that would be very helpful to give a more precise diagnosis)

Finally, that version of castep is 2 years out of date -- there is nothing in the release notes that especially relate to vector spins, but there are some improvements to algorithms that may make your calculations more efficient!

Hope that helps,

Rob

This looks like you're trying to do a spin-orbit calculation with ultrasoft pseudopotentials, which is not currently supported by CASTEP.

You can use Quantum Espresso instead of CASTEP. Spin-orbit coupling is easy in Quantum Espresso. You can take help of this paper given below for necessary codes:

Article Exploring the Impact of Strain on the Electronic and Optical...

Md. Harun-Or-Rashid that paper uses norm-conserving pseudopotentials for SOC, which are also fine with CASTEP. The original issue is trying to use *ultrasoft* pseudopotentials with SOC in CASTEP.

Philip James Hasnip You can also use *ultrasoft* pseudopotentials with SOC in Quantum Espresso. I have used that in my recently published paper as given below:

Article A Deep Analysis and Enhancing Photovoltaic Performance Above...