UT theoretical chemistry code forum

Dear Prof. Graeme and others,

I have used the SS-NEB with PSTRESS = 100 to perform the calculation, but the energy difference between the initial configure and the final configure is a little larger than that performed with VASP calculation, which I do not expect to occure. Is the SS-NEB calculation with external pressure set as accurate as the one without external pressure set?

Thank you very much.

I think we'll need some configuration and OUTCAR files to look into this.

The initial and final structures are not changed during SSNEB calculations. OUTCARs are copied to these two folders, so it is not SSNEB's problem.
But with PSTRESS, enthalpies in OSZICARs should be used instead of energies in OUTCARs in neb.dat. Be careful with nebbarrier.pl which reads energies from OUTCARs.

Is the converged saddle point structure different than the one without external pressure?

[quote="xph"]The initial and final structures are not changed during SSNEB calculations. OUTCARs are copied to these two folders, so it is not SSNEB's problem.
But with PSTRESS, enthalpies in OSZICARs should be used instead of energies in OUTCARs in neb.dat. Be careful with nebbarrier.pl which reads energies from OUTCARs.

Is the converged saddle point structure different than the one without external pressure?[/quote]
I have found the problem, just as you say, it is the problem of nebbarrier.pl.

Thank you.