Does somebody know how to resolve the error

Inv3 failed in PCMMkU.
 Error termination via Lnk1e in /g16/g16/l502.exe at Sat Jan 15 19:18:03 2022.

The input is

# opt=modredundant freq m062x/6-31g(d) scrf=(smd,solvent=n-Hexane)



I tried all the surfaces present in Gaussian (WdV, SAS and SES) but all of them returns the same error

This is the output of the log

Atomic radii for non-electrostatic terms: SMD-CDS.
 Nuclear repulsion after PCM non-electrostatic terms =     3242.6649455991 Hartrees.
 One-electron integrals computed using PRISM.
 NBasis=   514 RedAO= T EigKep=  4.41D-04  NBF=   514
 NBsUse=   514 1.00D-06 EigRej= -1.00D+00 NBFU=   514
 Lowest energy guess from the checkpoint file:  "chkname.chk"
 B after Tr=     0.000000    0.000000    0.000000
         Rot=    1.000000   -0.000006   -0.000001   -0.000002 Ang=  -0.00 deg.
 B after Tr=     0.000000    0.000000    0.000000
         Rot=    1.000000    0.000015    0.000003    0.000005 Ang=   0.00 deg.
 Requested convergence on RMS density matrix=1.00D-08 within 128 cycles.
 Requested convergence on MAX density matrix=1.00D-06.
 Requested convergence on             energy=1.00D-06.
 No special actions if energy rises.
 Inv3:  Mode=1 IEnd=    47664588.
 Iteration    1 A*A^-1 deviation from unit magnitude is 1.82D-12 for   2700.
 Iteration   10 A*A^-1 deviation from orthogonality  is 2.26D-09 for   2700   1612.
 Iteration   10 A^-1*A deviation from unit magnitude is 2.39D-09 for   2700.
 Iteration   10 A^-1*A deviation from orthogonality  is 3.47D-09 for   2700   1676.
 Inv3 failed in PCMMkU.
 Error termination via Lnk1e in /g16/g16/l502.exe at Sat Jan 15.
 Job cpu time:       8 days  6 hours  4 minutes  3.1 seconds.
 Elapsed time:       0 days  3 hours 25 minutes 24.9 seconds.
 File lengths (MBytes):  RWF=    688 Int=      0 D2E=      0 Chk=     28 Scr=      1

Another important this is that only with M06-2x functional throws this error.

  • 1
    $\begingroup$ Welcome to the site! Did this fail during the first SCF cycle or did it do a few geometry optimization steps before failing? What sort of initial geometry are you using (e.g. from some reference, made from scratch, calculation at lower level of theory, calculation with no/different solvent)? $\endgroup$
    – Tyberius
    Feb 5, 2022 at 14:40
  • $\begingroup$ @Tyberius I edited the code. I actually don't know where the step is. The initial geometry came from a previous calculation in gas phase. $\endgroup$ Feb 6, 2022 at 10:12
  • 1
    $\begingroup$ It looks like it has run for awhile, so this is failing after a few geom opt steps. If you only get this error with M06-2x, I would try to start the optimization with an optimized geometry from a different functional (say B3LYP or plain M06) using SMD, rather than a gas phase starting geom. Also, I don't have a great explanation of why this works, but in the past adding scrf=iterative has removed this error in problematic cases. $\endgroup$
    – Tyberius
    Feb 7, 2022 at 18:30
  • $\begingroup$ Any luck with either of my suggestions? $\endgroup$
    – Tyberius
    Feb 15, 2022 at 20:01
  • $\begingroup$ I tried again and, starting from a gas phase geometry, but with scrf=iterative the calculation converged. @Tyberius $\endgroup$ Mar 21, 2022 at 14:23

1 Answer 1


As suggested I changed the command line in

# opt=modredundant freq m062x/6-31g(d) scrf=(smd,solvent=n-Hexane,iterative)

And thanks to the iterative calculation of the SMD solvation, the geometry converged


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