RI-MP2/def2-tzvppd convergence issue for calculations with iodide

mdamer 2018-10-18 00:26:56 UTC #1

Hello,

I am struggling with getting my calculations to converge. I am ruunning interaction energy scan of iodide with benzene, nma and other compounds. I tried using SOSCF, MOM, DAMPING options but none is working. I uploaded the input and output for the case of NMA for you to have a look and hopefully you can tell me what am I doing wrong or what I can do to get to convergence.

Thank you,
Mirna

dimer.txt (3.2 KB)
dimer.dat (67.9 KB)

mdamer 2018-10-23 00:42:02 UTC #2

Hello,

Here is the error that I get :

=> Loading Basis Set <=

Name: ANONYMOUSA6868012
Role: ORBITAL
Keyword: BASIS
atoms 1, 3, 5, 7, 9, 11  entry C          line   144 file /home/mirna.damergi1/yes/envs/p4env/share/psi4/basis/def2-tzvppd.gbs
atoms 2, 4, 6, 8, 10, 12 entry H          line    14 file /home/mirna.damergi1/yes/envs/p4env/share/psi4/basis/def2-tzvppd.gbs
atoms 13                 entry I          line  2463 (ECP: line  3806) file /home/mirna.damergi1/yes/envs/p4env/share/psi4/basis/def2-tzvppd.gbs

!!!  WARNING: ECP capability is in beta. Please check occupations closely.  !!!

I tried to change the number of iterations (using maxiter), set SOSFC and MOM to true, set the orthogonalization to canonical. Yet, my systems with Iodide do not converge neither with def2-tzvppd or with def2-tzvpd.
Should I set SAD_FRAC_OCC to true ? This option appears below the Expert SAD Guess Algorithm.

Thank you for your help,
Mirna

dgasmith 2018-10-23 01:02:07 UTC #3

Sorry it took so long to get back to you. Looking at the output it appears that SOSCF does help considerably, you might try setting SOSCF_MAX_ITER = 15 and SOSCF_CONV=1.e-4 to tighten up the SOSCF iterations.

The next Psi4 release will also have the ability to do root finding for all SCF Wavefunction which might perform more optimally in this scenario as well.

mdamer 2018-10-23 03:50:02 UTC #4

Thank you for getting back at me. I will try this and let you know how it went.

mdamer 2018-10-25 21:34:29 UTC #5

Hello,

Unfortunately, although my calculations are getting to further steps, I still have a problem of convergence. Attached are two outputs from the same calculations.
The only difference is the range of distances I am using :

dimer.dat : 2.0 to 3.0 angstrom; ends successfully.
dimer2.dat : 3.0 to 5.0 angstrom; does not converge.
This brings me to a question, is it possible to continue the calculation when we fail to get to convergence ?

Thank you.

dimer.dat (583.7 KB)
dimer2.dat (431.2 KB)

Convergence algorithms

jmisiewicz 2018-11-14 11:29:36 UTC #6

While looking over your other topic, I noticed something dubious about your input file.

You are moving two ions away from each other but using a closed-shell reference. Have you tried switching to an open-shell reference, reference uks? It gets harder and harder to converge the closed-shell equations as the two parts of the system move away from each other, and the meaning of the closed-shell solution is less and less physical.

Also as I said in the other topic, try using guess read, so computations after your first one can use the orbitals from the previous geometry, which should be close to the ones you actually want.