Posted by Martín Amoza on September 16, 2015 at 11:06:35:

In Reply to: Re: CASPT2 convergence problem posted by Steven Vancoillie on September 14, 2015 at 08:48:49:

: : Dear all,

: : I'm running a CASPT2 calculation and I don't know why in the first CASPT2 state there aren't changes in the energies after the first iteration. Obviously the calculation end due to a convergence problem.

: Please show us the (relevant section) of the output.

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CASPT2 EQUATION SOLUTION

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Total nr of CASPT2 parameters:

Before reduction: 4737099455

After reduction: 4733177245

The contributions to the second order correlation energy in atomic units.

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IT. VJTU VJTI ATVX AIVX VJAI BVAT BJAT BJAI TOTAL RNORM

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1 -0.045206 -0.197027 -0.003909 -0.132927 -0.267595 -0.028323 -0.168419 -2.860558 -3.703965 0.049259

2 -0.045201 -0.197028 -0.003908 -0.132922 -0.267591 -0.028323 -0.168418 -2.860558 -3.703948 0.049263

3 -0.045201 -0.197028 -0.003908 -0.132922 -0.267591 -0.028323 -0.168418 -2.860558 -3.703948 0.049263

... (without changes)

298 -0.045201 -0.197028 -0.003908 -0.132922 -0.267591 -0.028323 -0.168418 -2.860558 -3.703948 0.049263

299 -0.045201 -0.197028 -0.003908 -0.132922 -0.267591 -0.028323 -0.168418 -2.860558 -3.703948 0.049263

300 -0.045201 -0.197028 -0.003908 -0.132922 -0.267591 -0.028323 -0.168418 -2.860558 -3.703948 0.049263

NOT CONVERGED AFTER MAX ITERATIONS.

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FINAL CASPT2 RESULT:

Reference energy: -3179.7931620580

E2 (Non-variational): -3.7039480453

E2 (Variational): -3.7136509790

Total energy: -3183.5068130370

Residual norm: 0.0492628791

Reference weight: 0.41017

Contributions to the CASPT2 correlation energy

Active & Virtual Only: -0.0322308639

One Inactive Excited: -0.3465409620

Two Inactive Excited: -3.3251762193

Total CASPT2 energies:

:: CASPT2 Root 1 Total energy: -3183.50681304

: : The previous RASSCF calculation ends normally so I don't know where can be the error.

: Even if rasscf ends "normally" it doesn't mean you have the correct reference wavefunction and that caspt2 will work without problems.

: Show us the output and tell us what you expected it to be.

I understand, I didn't express myself well. I wanted to said that the RASSCF calculations ends like similar calculations, that had worked before, without any unexpected output.

- Re: CASPT2 convergence problem
**Steven Vancoillie***08:25:36 9/18/15*(0)