NEVPT2 stops with error "Virtual block of Fock matrix not diagonal. Please use state specifc orbitals"

[葉哲和]

Dear Molpro users,

I was having a hard time with the NEVPT2 calculations using Molpro 2022 on my molecular system. It stops every time. At first I thought it was memory issue but enlarging memory didn't make things better. So I decided to do NEVPT2 with a single carbon atom, which I knew would work for my old Molpro 2012.

This input file worked for my old Molpro 2012. But whenever I tried my latest 2022.3.0 version it always showed this error message:

"? Error

 ? Virtual block of Fock matrix not diagonal. Please use state specifc orbitals

 ? The problem occurs in Readfm

 GLOBAL ERROR fehler on processor   0"

Have anyone had similar issue with this one? I searched through this mailing list and looked like someone else had this kind of issue except that he had it saying that "Closed orbital block of Fock matrix not diagonal."

I tried to compile Molpro 2021 and I still got this error message. However, Molpro 2020 worked ok, just like Molpro 2012 did. I could do this in the 2020 version but I do think there's a deciding factor that prevents this calculation to be done properly. Would someone explain please? Thanks in advance.

In brief,
Molpro 2012: works

Molpro 2015-2019: did not try but I think it works

Molpro 2020: works

Molpro 2021: does not work

Molpro 2022: does not work

I attach corresponding files in the attachment.

Best,
Che-Ho Yeh
National Yang-Ming Chiao-Tung University
Hsinchu City, Taiwan

[Gaurab Ganguly]

Hi  Che-Ho Yeh,

I had the same issue with NEVPT2 a few months back, and I wrote to Prof Werner. He suggested that likely the CI vectors in multi and nevpt2 were not exactly the same. He advised me to save the civectors in multi and reuse them is nevpt2. Note that the cirec numbers are increased by 100 for each additional state symmetry. 

Here I append a part of my NEVPT2/RASSCF input as an example:

!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
! RAS(13e,16o) 

!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

 {multi;config,csf;start,2142.2;
       !accuracy, gradient=1d-3, step=1d-4, energy=1d-5;
        frozen,   0, 0, 0, 0;
        closed,  32,24,24,15;
        occ,     39,26,26,20;
        wf,      nelec = 203, sym = 1, spin = 5, charge = 0;
        restrict, 0, 2, 38.1, 39.1, 18.4, 19.4, 20.4;
        restrict,-1,-1, 38.1, 39.1, 18.4, 19.4, 20.4;
        state, 1;
        wf,      nelec = 203, sym = 2, spin = 5, charge = 0;
        restrict, 0, 2, 38.1, 39.1, 18.4, 19.4, 20.4;
        restrict,-1,-1, 38.1, 39.1, 18.4, 19.4, 20.4;
        state,30;
        wf,      nelec = 203, sym = 3, spin = 5, charge = 0;
        restrict, 0, 2, 38.1, 39.1, 18.4, 19.4, 20.4;
        restrict,-1,-1, 38.1, 39.1, 18.4, 19.4, 20.4;
        state,30;
        natorb,2143.2, state = 1.1, cirec = 5143.2;
        natorb,2144.2, state = 3.2, cirec = 5144.2;
        natorb,2145.2, state = 5.2, cirec = 5145.2;}
        put,molden,ras_13e_16o.6a1.01.molden; orbital,2143.2;
        put,molden,ras_13e_16o.6b1.03.molden; orbital,2144.2;
        put,molden,ras_13e_16o.6b1.05.molden; orbital,2145.2;

!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
! NEVPT2
!+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 {nevpt2,cirec=5143.2,thrden=1.0d-8,thrvar=1.0d-8;
        maxit,   100,200;
        core,    15, 9, 9, 5;
        closed,  32,24,24,15;
        occ,     39,26,26,20;
        orbit,  2143.2, state = 1.1;
        wf,      nelec = 203, sym = 1, spin = 5, charge = 0;
        restrict, 0, 2, 38.1, 39.1, 18.4, 19.4, 20.4;
        restrict,-1,-1, 38.1, 39.1, 18.4, 19.4, 20.4;
        state,1,1}

 {nevpt2,cirec=5244.2,thrden=1.0d-8,thrvar=1.0d-8;
        maxit,   100,200;
        core,    15, 9, 9, 5;
        closed,  32,24,24,15;
        occ,     39,26,26,20;
        orbit,  2144.2, state = 3.2;
        wf,      nelec = 203, sym = 2, spin = 5, charge = 0;
        restrict, 0, 2, 38.1, 39.1, 18.4, 19.4, 20.4;
        restrict,-1,-1, 38.1, 39.1, 18.4, 19.4, 20.4;
        state,1,3}

 {nevpt2,cirec=5245.2,thrden=1.0d-8,thrvar=1.0d-8;
        maxit,   100,200;
        core,    15, 9, 9, 5;
        closed,  32,24,24,15;
        occ,     39,26,26,20;
        orbit,  2145.2, state = 5.2;
        wf,      nelec = 203, sym = 2, spin = 5, charge = 0;
        restrict, 0, 2, 38.1, 39.1, 18.4, 19.4, 20.4;
        restrict,-1,-1, 38.1, 39.1, 18.4, 19.4, 20.4;
        state,1,5}

I hope this will help resolve your problem.

best,

Gaurab

Gaurab Ganguly

Postdoc, IOCB Prague