H2 dissociation with UHF

[Lexin Ding]

Hi everyone,

I am trying to get a symmetry-broken solution of the H2 ground state using the UHF method. In an old correspondence by Werner he suggested the following:

"

symmetry broken starting orbitals...can be obtained by first doing a rhf calculation for the triplet, and then rotating the two open-shell orbitals by 45 degrees (using ROTATE). This input does the job: geometry={x,y;h1;h2,h1,r} r=4 hf;wf,spin=2 uhf;wf,spin=0;rotate,1.1,2.1,45

"

I tried this input but it doesn't work. I assume the syntax has already been updated. I used the following input instead

"

geometry={

H1

H2 H1 r(i)}

{hf,

wf,2,1,2

}

{uhf,

wf,2,1,0,

rotate,1.1,2.1,45}

"

But the hf and uhf energy still coincide, namely the symmetry is still not broken in the uhf process. Does anyone have a solution around this? Thanks very much in advance!

Best wishes,

Lexin

[Yuri Alexandre Aoto]

Hi Lexin,

you need the keyword "nosym", or "nosymmetry", before the geometry to have a symmetry broken solution, otherwise symmetry is enforced by default.

yuri

--
You received this message because you are subscribed to the Google Groups "molpro-user" group.
To unsubscribe from this group and stop receiving emails from it, send an email to molpro-user...@googlegroups.com.
To view this discussion on the web, visit https://groups.google.com/d/msgid/molpro-user/7778444f-38ed-4871-b81c-b6f838c09ee7n%40googlegroups.com.

[Lexin Ding]

Thanks a lot! That worked like a charm :).

Best wishes,

Lexin