QuantumATK Forum

QuantumATK => General Questions and Answers => Topic started by: gayani2025 on August 1, 2025, 05:02

Title: Ni Spin down relaxes to spin up during the transmission calculation
Post by: gayani2025 on August 1, 2025, 05:02

Dear All,

I am currently performing a spin transport calculation using QuantumATK, where the left electrode is Nickel (Ni) and the right electrode is Gold (Au). An organic molecule is placed in the central region between the electrodes.

In the setup, I initialized the Ni atoms with both spin-up and spin-down configurations in separate calculations, while keeping all other atoms non-magnetic (zero initial spin). However, in both cases, the transmission spectrum turned out to be almost identical.
(Ni electrode=2.5V Au=0V)

Upon inspecting the Mulliken spin population, I observed that even when I initialized Ni with spin-down, the calculation converged to a spin-up state. It appears that the system spontaneously flips the spin during relaxation.

I’ve attached the relevant input  (py)and output figures as well as a PDF  for your reference.

I would greatly appreciate any guidance on how to enforce a stable spin-down state on the Ni electrode, as I’m trying to study how the transmission spectrum changes when the Ni tip is spin-up versus spin-down.

Looking forward to your suggestions.

Thanks
Gayani

Title: Re: Ni Spin down relaxes to spin up during the transmission calculation
Post by: prayash on August 10, 2025, 01:55

Hi Gayani,
Did you find a solution? I have the same problem: I can't correctly fix the spins even after using FixedSpin on my noncollinear device.

Title: Re: Ni Spin down relaxes to spin up during the transmission calculation
Post by: gayani2025 on August 11, 2025, 05:30

Hii,

No actually I also could not fix the spin yet.

Best wishes
Gayani