Fixing the spin at each atom

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Fixing the spin at each atom

Post by senersen » Fri Aug 05, 2016 12:10 pm

Dear users

I have a problem which can be (i think) solved by fixing the spin value at each atom. The problem is as follows;

I am trying to calculate the ground state of an anti-ferromagnetic (AFM) system. Although i know the value of final spins approximately, i do not know the lattice constant and position of the atoms for that system. When i start from the spin unpolarized geometry or from AFM geometry obtained with some other pseudopotential i get 0 magnetic moment at each atom. Therefore, i thought, to be sure that i cannot have AFM state with this pseudopotential, i need to fix the spin of each atom to the value that i expect and relax the system for the geometry. Then, after obtaining the optimized geometry i can relax the geometry and spin values together to see if it is going to go zero again or give me some spin value.

I could not find a variable that tells abinit to keep the spin at each atom fixed. Does anyone know how to do it or how to solve my problem woth some other method?



Posts: 370
Joined: Tue Apr 19, 2011 11:13 am
Location: University of Liege, Belgium

Re: Fixing the spin at each atom

Post by ebousquet » Fri Aug 12, 2016 12:24 pm

Dear Sener,
You have the magconon and magcon_lambda input variables to fix the spin value on each atom:
It should constrain the magnetisation in a sphere around each atom to the one you specify in the spinat input flag.
You'll have to play a bit with the constraint factor lambda to find the right regime.
Best wishes,

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