IRC failing to converge with IRCInnerLoopConvergenceFailure

[Youbin-K]

Hi, I'm trying to run the IRC in metal slab systems, where it gives me the error of

sella.optimize.irc.IRCInnerLoopConvergenceFailure

Below is the out file:

---

Running relaxation using VaspInteractive

---

 Step     Time          Energy         fmax

IRC: 0 18:25:51 -166.366325 0.0239
Trying to close the VASP stream but encountered error:
Traceback (most recent call last):
File "/gpfs/scratch/ykim219/IRC_test/CCH3/relax_with_VASPInteractive.py", line 51, in run_vasp_interactive
opt.run(fmax=0.025, steps=1000, direction='forward')
File "/users/ykim219/.local/lib/python3.9/site-packages/sella/optimize/irc.py", line 101, in run
for converged in self.irun(fmax, fmax_inner, steps, direction):
sella.optimize.irc.IRCInnerLoopConvergenceFailure

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/users/ykim219/.local/lib/python3.9/site-packages/vasp_interactive/vasp_interactive.py", line 1015, in _force_kill_process
self.close()
File "/users/ykim219/.local/lib/python3.9/site-packages/vasp_interactive/vasp_interactive.py", line 598, in close
self._run(self.atoms, out=out, require_cell_stdin=False)
vasp_interactive.utils.TimeoutException: Timed out closing VASP process.

Will now force closing the VASP process. The OUTCAR and vasprun.xml outputs may be incomplete
Traceback (most recent call last):
File "/gpfs/scratch/ykim219/IRC_test/CCH3/relax_with_VASPInteractive.py", line 57, in
run_vasp_interactive()
File "/gpfs/scratch/ykim219/IRC_test/CCH3/relax_with_VASPInteractive.py", line 51, in run_vasp_interactive
opt.run(fmax=0.025, steps=1000, direction='forward')
File "/users/ykim219/.local/lib/python3.9/site-packages/sella/optimize/irc.py", line 101, in run
for converged in self.irun(fmax, fmax_inner, steps, direction):
File "/gpfs/data/cfgoldsm/ykim219/Research/Source_files/ase/ase_3.22.1/ase/optimize/optimize.py", line 135, in irun
self.step()
File "/users/ykim219/.local/lib/python3.9/site-packages/sella/optimize/irc.py", line 138, in step
raise IRCInnerLoopConvergenceFailure
sella.optimize.irc.IRCInnerLoopConvergenceFailure

Would this possibly be due to the compatibility of the VASPinteractive and Sella? Or is this because of the algorithm of the IRC?

[ehermes]

This is probably caused by poor gradient precision in the inner loop. Can you try tightening your SCF convergence parameters? It's been a while since I've used VASP so I can't remember which parameters control its SCF convergence threshold...

[Youbin-K]

Hi, I tried tightening the SCF convergence parameter from 1e-5 to 1e-6 and 1e-7, which both also fails with the same errors.
I've also tried to run with increased steps by dx=0.1 to dx=0.3, which also gives the same errors. Would it be worth trying to change the 'eta' value in the IRC and the 'steps' in the forward and reverse directions?