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Questions tagged [casscf]

For questions about performing Complete Active Space Self Consistent Field calculations

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An excited state for a molecule, Molpro, casscf

I tried my best to bring an iodine molecule to an excited state to investigate orbital 4.3 but all my atteps were not successful. So, here is the file in molpro for the groundstate ...
Tkt's user avatar
  • 41
1 vote
1 answer
97 views

Spin Configuration of Active Space in PySCF

I was running a state averaged CASSCF (4,4) calculation for the first 3 roots of the TMM biradical in PySCF. I wanted to get the spin configuration of the active space but the only information I could ...
Abhishek R Nath's user avatar
4 votes
1 answer
73 views

Table of Largest CI Components in PySCF CASSCF Calculation

I was running a simple CASSCF calculation in PySCF on the TMM biradical. It was a CASSCF (4,4) state averaged calculation where the energies of the first 3 roots were calculated. The simulation output ...
Abhishek R Nath's user avatar
7 votes
2 answers
350 views

Choosing an active space for CASSCF using Molpro

I am trying to determine the potential energy curves for a CH2Cl radical by varying the C-Cl distance. For that I use the CASSCF method In MOLPRO with the aug-cc-pVTZ basis set, I didn't get smooth ...
Fatma's user avatar
  • 71
2 votes
1 answer
595 views

How to choose the number of roots in a CASSCF calculation?

What are the criteria that one has to consider while chosing the number of roots in a CASSCF calculation?
Aritra Mukhopadhyaya's user avatar
4 votes
1 answer
350 views

How many electrons and orbitals should I include in a CASSCF calculation?

I'm interested in running CASSCF calculations to get a dissociation curve for a number of systems of the form: atom-atom, atom-diatomic or diatomic-diatomic (e.g. Li+ ... O-, K+ ... O2, or N(3-) ... ...
Alex I's user avatar
  • 1,038
4 votes
0 answers
110 views

Setting a frozen core in Molpro

I am carrying out a project which involves obtaining the RHF result and the integrals for the chromium dimer (Cr2) under Ahlrichs' SV basis. In the literature against which we attempt to benchmark, ...
Izzy Vang's user avatar
9 votes
1 answer
140 views

Which molecules have multi-reference character?

I'm using WebMO to construct molecules that have high multireference character, but I cannot seem to find any, or perhaps I'm not building them correctly on WebMO; I know singlet biradicals generally ...
MajesticMarkUp's user avatar
7 votes
3 answers
529 views

Open source FCI solvers for exact diagonalization of the many-electron Hamiltonian

What open source solvers (according to the generally accepted Open Source Definition i.e. licensed under a valid open source license) are available for full configuration interaction calculations? ...
Susi Lehtola's user avatar
  • 19.7k
7 votes
1 answer
246 views

Frequency error in Gaussian CASSCF(10,10)

I am stuck in calculating the frequencies of one optimised geometry for naphthalene CASSCF(10,10) with Gaussian 16. I have optimised its geometry and checked the active space is the pi system of it, ...
Paul Logan's user avatar
5 votes
1 answer
838 views

Modify ORCA orbitals for CASSCF

I have run a HF calculation on naphthalene and I have checked the MOs that have been obtained. Now, I have to select my active and inactive orbitals for CASCF(10,10). As there are 34 occupied orbitals,...
Paul Logan's user avatar
10 votes
1 answer
797 views

Molecular orbitals and active space

During the same minute as asking this question, I also asked this at Quantum Computing SE. In Qiskit, each qubit corresponds to one spin orbital. For example, the $\ce{N2}$ molecule would have 10 ...
ironmanaudi's user avatar
4 votes
0 answers
117 views

Calculating wave-function overlap in MOLPRO

Is it possible to somehow calculate the inner product (or overlap) between the electronic wave-functions of excited states in Molpro? What I want to do is to compare the electronic wave-functions that ...
stack-delay's user avatar
5 votes
1 answer
194 views

In Molpro, how to calculate the orbital angular momentum?

I wish to calculate the values of the orbital angular momentum of excited electronic states, using Molpro. So $\langle L_x \rangle$, $\langle L_y \rangle$, and $\langle L_z \rangle$. (Specifically for ...
stack-delay's user avatar
9 votes
2 answers
721 views

How does MOLPRO choose active orbitals in a CASSCF calculation?

I am trying to calculate electronically excited states for the CO molecule, with the aug-cc-pVTZ basis set, and a CASSCF calculation. The documentation describes ...
stack-delay's user avatar
4 votes
2 answers
104 views

CASSCF and thermochemistry—effect of excited determinants on rotational and vibrational modes

So this question is linked to the other question I asked about the electronic patition function and CASSCF. When calculating thermochemical data (e.g. Gibbs Free energy) the partition functions are ...
S R Maiti's user avatar
  • 6,991
4 votes
1 answer
210 views

Excited determinants, electronic partition function and thermochemistry calculation

While studying statistical thermodynamics I came across the partition functions, which connect the quantum world to the macroscopic world. I understand that partition functions are used to calculate ...
S R Maiti's user avatar
  • 6,991
10 votes
1 answer
559 views

How to determine occupied and closed orbitals for a Molpro CASSCF calculation?

I am currently working with Molpro, to which I am completely new, trying to run some calculations on $\ce{PdO}$. From literature I have gathered that the ground state is given by $^3\Sigma^-$ state, ...
ABCCHEM's user avatar
  • 103
8 votes
0 answers
109 views

How to classify ionic and covalent excited-states? [closed]

In spectroscopy it is common to describe excited-states as ionic or covalent. I understand the concept on a toy model e.g. $\ce{H2}$ with a minimal basis set \begin{align} \Phi_0 &= [\chi_A(1) + \...
Cody Aldaz's user avatar
  • 8,017
15 votes
1 answer
299 views

What are the ways to add dynamic correlation to an MCSCF wavefunction?

We recently learned about the many types of MCSCF, which treat "static" electron correlation. There are then many ways to treat further "dynamic" electron correlation to try and ...
Nike Dattani - No Free Time's user avatar
19 votes
3 answers
418 views

What are the types of MCSCF?

Similar to: What are the types of SCF? What are the types of Quantum Monte Carlo? What are the types of ab initio Molecular Dynamics? What are the types of pseudopotentials? What are the types of DFT?...
Nike Dattani - No Free Time's user avatar
9 votes
1 answer
224 views

Can MOLPRO (2012) calculate SA-CASSCF gradients with cc-pVDZ?

I have tried to calculate state-averaged gradients with MOLPRO using the default basis set cc-pvdz. However, I was met with the error message: ...
Cody Aldaz's user avatar
  • 8,017
34 votes
9 answers
2k views

Is there a free package with robust CASSCF functionality?

Among free software packages, which one has robust CASSCF functionality? The FCI solver can be implemented in either way, e.g., direct solver, DMRG, etc.
Yingzhou Li's user avatar
  • 1,086