Issue with S₁ State Optimization Under PCM – SCF Convergence Error

Questions
#1

Dear Q-Chem Developers and Users,

I am attempting to perform an S₁ excited-state geometry optimization under PCM conditions. However, the calculation consistently fails with an SCF convergence error.
The input file used is provided below:

$molecule
read opt.txt
$end

$rem
jobtype opt
METHOD wB97X-D
BASIS 6-31+G(d,p)
XC_GRID 000099000590
CIS_STATE_DERIV 1
CIS_N_ROOTS 3
CIS_SINGLETS TRUE
CIS_TRIPLETS FALSE
STATE_FOLLOW TRUE
max_scf_cycles 500
SCF_CONVERGENCE 8
THRESH 12
INCDFT FALSE
mem_static 4000
MEM_TOTAL 32000
MOLDEN_FORMAT TRUE
SYMMETRY FALSE
SYM_IGNORE TRUE
SOLVENT_METHOD PCM
$end

$pcm
Theory IEFPCM
Method SWIG
Solver Inversion
Heavypoints 194
Hpoints 194
Radii Bondi
VdwScale 1.2
$end

$solvent
Dielectric 24.3
$end

Key error excerpt from the output file:
gen_scfman_exception: SCF failed to converge

Q-Chem fatal error occurred in module libgscf/gen_scfman/gen_scfman_main.C, line 243:

Error in gen_scfman

Please submit a crash report at Q-Chem Crash Reporter

I would greatly appreciate any assistance or insights you might offer to help resolve this issue. Thank you for your time and consideration.

#2

We would need more information (like a complete input file) to diagnose this. Take a look at the geometry and make sure it’s not doing anything crazy like dissociating an atom, which leads to a challenging SCF problem. Otherwise, you need to vary SCF_ALGORITHM to try to find a converged solution. From Q-Chem v. 6.3 you can try SCF_ALGORITHM = ROBUST to try various alternatives automatically.

#3

Thank you, Prof. Herbert. I inspected the intermediate geometries and observed that some bonds are indeed elongating and breaking during the S₁ optimization. Could you please advise on how to resolve this issue?

#4

See above regarding SCF_ALGORITHM.