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#1 2020-12-14 11:45:50

vkj
Member
Registered: 2019-04-10
Posts: 29

NTO ( from RASSI) vs Natural orbitals from RASSCF

Are the NTO's generated using NTOCALC keyword in rassi equivalent to natural orbitals generated by rasscf module ?

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#2 2020-12-14 13:40:30

Ignacio
Administrator
From: Uppsala
Registered: 2015-11-03
Posts: 1,085

Re: NTO ( from RASSI) vs Natural orbitals from RASSCF

They should be, but with RASSI you can mix different RASSCF calculations, which could have differet spin or spatial symmetry.

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#3 2021-01-14 21:23:06

felixp
Member
Registered: 2015-11-06
Posts: 27
Website

Re: NTO ( from RASSI) vs Natural orbitals from RASSCF

If you have a correlated wavefunction, then there is actually no reason to assume that the NTOs should be the same as the NOs. They are determined as the eigenvectors of different matrices and will differ in general.

If you just want an example of how things may differ, you can check Fig. 6 of [DOI: 10.1021/acs.chemrev.8b00244]. If you are interested into the full theory, check [DOI: 10.1063/1.4885819 + 10.1063/1.4885820].

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#4 2021-01-15 09:47:06

Ignacio
Administrator
From: Uppsala
Registered: 2015-11-03
Posts: 1,085

Re: NTO ( from RASSI) vs Natural orbitals from RASSCF

Of course, I meant they should be the same as the natural transition orbitals that can be calculated in RASSCF (or actually, displayed with Pegamoid from a RASSCF calculation with the TDM keyword).

And although they're in general different from the plain natural orbitals, they still span the same space.

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