Termination during Potential Surface Scans using CCSD(T) with ANO-DK3 basis set

Hello everyone,
I want to calculate the potential energy curve of Si2 and Be2, the code as following:

molecule Si2 {
  Si 1 R_Val


set basis ANO-DK3
set reference uhf
Si2_E = optimize('ccsd(t)')

psi4.print_out("CCSD(T)/cc-pVQZ interaction energies\n\n")
psi4.print_out("        R [Ang]         E_int [eV]             \n")
e = Si2_E * psi_hartree2ev 
psi4.print_out("        %3.1f            %10.6f\n" % (Si2.R_Val, e))  

but meet the questions as following:

  1. Element = Si, R=6.
    The program stopped with “Fatal Error: Timer ccenergy is not on.”
    The report in output.dat show "** Wave function not converged to 1.0e-07 ** " in Solving CC Amplitude Equations section.
  2. Element = Be, R=3:
    The program report the warning “forrtl: severe (71): integer divide by zero”
    In output.dat, there is nothing after"Size of irrep 7 of tijab amplitudes: 0.000 (MW) / 0.000 (MB) \n Total: 0.000 (MW) / 0.003 (MB) "

How can I solve these problem?
P.S. The ANO-DK3 were downloaded from: https://www.basissetexchange.org/
All the best,
Zhenbang Wei

It looks like your issue with Si2 is the same as here. The CC equations aren’t converging…

@hokru, did you look into the convergence failures after your last post on that topic?

I don’t know what the problem with Be2 is, but I suspect that’s a Psi4 bug where we are somewhere assuming that every irrep has amplitudes. I’ll do some preliminary investigating later today and get an issue filed if it indeed seems to be a Psi bug.

No I don’t think I did.

I can’t reproduce the Be problem with my version of Psi4.

For beryllium, what version of Psi4 are you using? It will tell you at the start of your output file. See instruction 5 if you don’t know how to find it.

If you aren’t using version 1.3.2, try using a newer version of Psi4.