Questions tagged [orca]
For questions about (or involving) the ORCA electronic-structure package.
11 questions with no upvoted or accepted answers
5
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How to calculate singlet-triplet splitting energy with TD-DFT in ORCA?
I wish to reproduce the results from this paper by Truhlar and co-workers, where they treat a spin-forbidden reaction by considering two effective states coupled by a semi-empirical spin-orbit ...
- 7,171
5
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91
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Does a TD-DFT excitation from a closed-shell determinant only include the alpha electron part?
From an input in ORCA 5.0.3
! PBE 6-31G*
%TDDFT NROOTS
3
END
* xyz 0 1
H 0. 0. 0.
H 0. 0. 0.7414
*
the output includes
...
- 51
4
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29
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How to plot orbitals for S1->T1 transition in Orca
I use TD-DFT and want to examine how molecular orbital changes upon ISC from S1 to Tx state and refer to confirm El Sayed rule. How to achieve it if NTO are not generated for S1->Tx transitions? If ...
- 563
4
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94
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How to compute only part of molecular Hessian accurately (hybrid Hessian or partial Hessian calculation)?
Hessian is required for minimisation and transition state (TS) optimisation algorithms. While the full Hessian at a certain level of theory is calculated usually for TS optimisation, usually ...
- 7,171
4
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0
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305
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orca_vpot problem
I'm trying to calculate the electrostatic potential of a molecule. When I try to use the orca_vpot tool, I am facing some difficulties detailed below.
The first ...
- 41
3
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0
answers
31
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How can the singlet wavefunction be used for a triplet calculation?
I am performing a single-point calculation in ORCA to determine the singlet excited state energies. I also want to calculate the triplet state energies, but I've noticed something that seems incorrect....
- 1,652
3
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0
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38
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IRC calculation shows a maximum in one direction
I am doing IRC calculations on transition-states of organometallic compounds with ORCA. While I only find one imaginary mode for the transition state which corresponds to the expected vibration, ...
- 331
3
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0
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94
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Obtain force constants from normal modes
I am trying to reproduce an QTAIM analysis by Foroutan-Nejad et al. (https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/chem.201402177). Instead of only looking into the equilibrium ...
- 331
3
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0
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95
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How to calculate Gibbs free energy of a reaction involving cations using GFN2-xTB (via ORCA)
I am trying to compare the Gibbs free energy of reactions such as:
A + 4K(+) --> B(4+)
A + 4Na(+) --> C(4+)
A + 4Li(+) --> D(4+)
A + 4Ca(2+) --> E(8+)
A + 4Mg(2+) --> F(8+)
In these ...
- 131
3
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0
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92
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How to generate .47 files from ORCA-5.0.3 ? Also, can we analyze the second order perturbation energy analysis within the nbo scheme using GENNBO?
I am using ORCA-5.0.3 as ESS package and our group has also recently purchased nbo7 which is not interfaced with the ESS. I had tried multiple ways to generate .47 file but couldn't succeed and am ...
- 31
2
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219
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Error: Cannot open GBW file: TS.gbw
I have a problem with calculating Transition State using NEB-TS. Here is my input file:
...
- 21