Iv curve converged in ONE step!?

[ktchavan]

Hi,

I attempted IV curve calculations for MTJ device for the range of bias from -1.0V to 1.0V in steps of 0.05V. The geometry was relaxed up to max force tolerance 0.01eV/A. K point sampling 11*11*171 and density mesh cutoff 110Ha used. Maximum steps 200 was set.

IV curve calculations calculation were converged for all +ve voltages and for few -ve voltages up to -0.40V. Beyond that, for -0.45V to -0.60V, it not converged BUT after that for -0.65V to -1.0V converged in ONE step with ~zero current.

Its hard to me to believe convergence in one step for such case. How can I validate it?

Regards
Kashinath

[Ulrik G. Vej-Hansen]

You can look at the log-file, and see if the density matrix values look reasonable. My guess is that they do not, as you kept starting from an unconverged result. Based on what you write here, you need to go back to -0.45 V and modify the calculator so it converges. See our guide here: https://docs.quantumwise.com/technicalnotes/negf_convergence_guide/negf_convergence_guide.html