[ADF-LIST] Best restart practices for SCF convergence

Tim Wilson twilson at mymail.mines.edu
Tue Jan 16 21:49:48 CET 2018

I have two use cases in which SCF convergence is inadequate and I’d like some advice.

First, I have some large metal cluster single point calculations that are difficult to converge. These are running on a cluster with a runtime limit (6 days) that is too low for me to finish the single point job in one run. If I employ smearing I can get a cluster to converge at, e.g., 1Ry. In a single job I can achieve convergence through about 5 smearing steps (from 1Ry to 0.1Ry) before I approach the runtime limit. I then use the TAPE21 from the previous job converged at 0.1Ry smearing, and start a new job that lowers smearing through another 5 steps starting at 0.1Ry (the smearing level at which the previous converged job finished). However, the restart job fails to converge at 0.1Ry smearing, even though the previous job converged.

Second, when restarting using a converged TAPE21 for the sole purpose of performing Bader analysis (on the same metal cluster, assuming it’s fully converged at ground state), the SCF might fail to converge, even though the job was provided with a converged TAPE21 for the same system. In this case, it seems ADF should simply see that the restart TAPE21 contains a successful converged termination status and just bypass the SCF procedure.

I see in the documentation that:

"The SCF and optimization procedures use history to improve convergence behavior. Most of such history information is not stored on a restart file. As a consequence, a restart may not continue exactly as the original run would have done if it hadn’t terminated.”

With that in mind, I imagine that there are guidelines for utilizing a converged restart file for the use cases described above that will best accelerate SCF convergence upon restart?



Tim Wilson
Colorado School of Mines — Applied Chemistry
Molecular Theory Group — Research Associate

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