A data base of errors encountered when running gaussian jobs

simple errors

Convergence failure -- run terminated. your SCF is not converged solution
if your checkpoint file is not present it cannot be read:

check that your input file name and checkpoint filename are exactly the same

your checkpoint file could be corrupted

you will have to start without the checkpoint file so remove any guess=read geom=checkpoint commands

 
Number           0
 Base         40448
 End          65536
 End1         65536
 Wr Pntr      40448
 Rd Pntr      40448
 Length       25088
 Error termination in NtrErr:
 NtrErr Called from FileIO.

Warning -- assumption of classical behavior for rotation may cause significant error

this error is not well defined, it likely means the rigid rotor approximation may be inaccurate, this makes sense with the following error which indicates low energy motions, as a molecule expands and contracts its rotational energy changes and so the rigid rotor approximation may not be a good one.

Warning -- assumption of classical behavior for rotation may cause significant error

this is a common error when you work out the entropy of a system you need to separate out the rotational motion from the vibrational motions as they have different formulae. When the energy of the vibrational mode is very low it it could be a hindered rotation (often found for methyl groups), however gaussian will treat it as a vibration in the entropy formula. All vibrations below 900K receive this warning message. In addition this mode is so low in energy, that the assumption that ony the ground state is occupied is breaking down and there can be more than 5% of molecules in excited vibrational state (per vibration!) The errors involved are very small for us and so it is normal to ignore this error.

take a look at the "thermochemistry" white paper on the gaussian website link

a potential correction is to use the Freq=HindRot but this is an advanced option with some complex underlying issues and you should read the literature before using it!

complex errors

my optimisation shows convergence, but the frequency job restarted from this is NOT converged! solution
can not run job from checkpoint file because of a read and write error (FileIO) solution
AIM doesn't work for planar ring structures

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