Re: Are there restrictions to the number of active/inactive orbitals in GUGA?

Subject:

if B is 1s22s22p1, what is Li?

Passfield:

Comments:
: Dear Evgeniy, : Sorry for the late answer! : There is a limit to the number of orbitals, but this is not the reason that your : calculation failed. : First of all, GUGA is concerned only with the correlated electrons, and only : with the inactive and active orbitals. The number of virtual orbitals becomes interesting : only in a subsequent CI or CPF calculation. Your calculation askes to correlate 84 : electrons, which are in a reference space of 41 inactive and 2 active orbitals. The : calculation is not really large. This gives rise to 'internal' configurations: Valence states(946), doublet-coupled singles(3528), etc, altogether a little more than 9000. : The reason that the calculation failes is just one single array, unfortunately not : dynamically allocated, which was dimensioned for 14000 items, but now needed almost the : double. You can increase the parameter MXCASE to 28000 (say) in integ.inc, and the : calculation will pass after recompilation. I will make a similar patch, but will try and : see if I can make the array dynamical. : The code is very old, and is difficult to maintain properly. Also, it is not written : to be very effective with large incative spaces: The so-called internal coupling : coefficients are computed and put on a file, to be used by the MRCI or MR-ACPF: this file : is (in your case) about 730 MBytes. However, it is also a matter of whether a calculation such as yours is very meaningful. The size consistency errors will be large, and the correlation contribution from external excitations will be very modest given the small basis set. : Best regards, : PÅ : NUMBER OF VALENCE STATES 946 : NUMBER OF DOUBLET COUPLED SINGLES 3528 : NUMBER OF TRIPLET COUPLED DOUBLES 2542 : NUMBER OF SINGLET COUPLED DOUBLES 2666 : : Dear All! : : First, I'd like to thank Luis Serrano for replying in detail to my previous post (about CASPT2). I might return to the CASPT2 problems in next poster but now I'd like to ask about the performance of GUGA. Namely I wonder whether there are some restrictions to the number of active and correlated (inactive) orbitals in GUGA. More precisely I would like to perform CISD for a 84 electron system and I am interested in the two lowest states, S0 and S1. Unfortunately my input (given below) does't work, crashing at the GUGA step. So, I wonder whether this is due to internal limitations or there is some error in the input. Many thanks! : : Best, : : Evgeniy : : &SEWARD &END : : Title : : pCTA(H2O)2 Alpha twisted structure : : coord : : geom.xyz : : basis : : sto-3g : : group : : c1 : : End of input : : &SCF &END : : Charge : : -1 : : End of input : : &MOTRA &END : : Frozen : : 19 : : End of input : : &GUGA &END : : Electrons : : 84 : : Spin : : 1 : : Active : : 2 : : Inactive : : 41 : : End of input