Questions tagged [orca]

For questions about (or involving) the ORCA electronic-structure package.

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QuasiRRHO in Orca

I read that ORCA runs a QuasiRRHO calculation based on Grimme approximation, at the end of a freq calculation. Unfortunately, I wasn't able to find the default value for the CutOffFreq. In Grimme's ...
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5 votes
1 answer
60 views

Successfully running parallel gas phase calculation on AMD cloud instance but implicit solvent fails (Local Intel workstation successfully runs both)

I am using an AMD Linux cloud-based instance to ran general optimisation and transition state calculations in parallel. I have noticed that I can run gas phase calculations in parallel but the run ...
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5 votes
2 answers
110 views

ORCA: Dipole moment of LiH from SP calculation

I calculate LiH with ORCA ...
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5 votes
1 answer
210 views

Bromine basis set problem

I'm trying to compute the energy of the benzyl bromide with orca. I need it to be at ωB97x-d4/6-31g(d) level. Orca throws me the following error. ...
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5 votes
1 answer
54 views

ORCA: CIS calculation for Helium atom

I want to understand ORCA output for CIS calculations. From the input file ...
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5 votes
0 answers
33 views

MOLDEN file from ORCA output

I'm trying to convert an ORCA output file into MOLDEN file (via molden itself). I hit the "Write" button and it converts the file, yes, but the displacement vector s are zeros. I need that ...
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4 votes
1 answer
146 views

ORCA: meaning of numbers in ORCA.out of MOLECULAR ORBITALS for STO-3G Lithium

For Lithium STO-3G basis set ...
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3 votes
1 answer
44 views

Non-equilibrium CPCM for Orca Absorption Spectra

I run into this article[1] in which they figure out that if you want to correctly simulate electronic spectra you have to consider the non-equilibrium solvation. I've made research into the ...
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3 votes
0 answers
71 views

Segmentation fault with ORCA-3.0.1

I would like to use ORCA-3.0.1 under the following Linux version: 5.10.0-10-amd64 #1 SMP Debian 5.10.84-1 (2021-12-08) x86_64 GNU/Linux and Intel version ...
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4 votes
0 answers
81 views

STEOM-DLPNO-CCSD

I have to calculate the S1 - T1 energy gap using coupled cluster (STEOM-DLPNO-CCSD) in ORCA. The output file contains only singlet energies. IROOT=... (no notation singlet or triplet). I tried adding &...
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7 votes
2 answers
278 views

Different types of transition dipole moment in ORCA output

In the ORCA output for a TD-DFT calculation, there are two types of spectra printed. One is called "transition electric dipole moment" and "transition velocty dipole moment". ...
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7 votes
1 answer
173 views

What are the output files generated by an NEB calculation?

I just used Orca for the first time. Can someone address me a valid guide to understand all the files in the directory? I'd like to perform a Nudged Elastic Band (NEB) calculation, but I'm stuck ...
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6 votes
1 answer
123 views

Is It possible to do microkinetic modelling for liquid phase reactions, in the presence of a catalyst?

As from the title, I want to do NEB-TS for chemical reactions in the liquid phase, and use the information to calculate reaction rates/kinetic rates. I know that the NEB-TS is possible in the liquid ...
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5 votes
1 answer
214 views

Unrecognized or duplicated keyword error using ORCA

I wanted to run ORCA 5.0.2 with the following input: ...
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6 votes
0 answers
103 views

How do you perform parallelization of NEB-TS in ORCA? [closed]

I have tried running a NEB-TS calculation in orca with %pal nprocs 32, but I get an error saying ...
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6 votes
1 answer
604 views

How to properly define %maxcore in ORCA

The %maxcore parameter in ORCA gives the memory per core needed for a calculation, however it is unclear to me if this should be the entire memory available to the ...
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5 votes
1 answer
120 views

Numerical Frequency Parallelization in ORCA

In orca it is possible to use NumFreq and AnFreq to get the numerical and analytical frequencies, but the analytical frequencies take a large amount of memory and computing time compared to numerical ...
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5 votes
1 answer
155 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,...
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11 votes
3 answers
230 views

Quantum chemistry in external electrostatic field?

Which quantum chemistry methods can be used in an external electrostatic field? Also which software supports that? I'm interested in anything from semiempirical (eg XTB) to DFT (eg ωB97, B3LYP-D3) ...
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7 votes
1 answer
484 views

How can I calculate the energy gap between the singlet and triplet state using ORCA?

I came across this publication that calculates the $S_1$ - $T_1$ energy gap using TDDFT as implemented in Gaussian. I would like to do the same using ORCA. Im extremely new to ORCA and local orbital ...
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7 votes
1 answer
480 views

Why is my ORCA calculation of nitrogen iodide failing?

I am using ORCA version 4.2.1 to calculate on the RI-BP86/def2-SVP level of theory the molecule $\ce{NI3}$. I would assume this to be a rather trivial matter, but I am running into an error. I've only ...
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11 votes
1 answer
169 views

Using "soft" constraints / bias in geometry optimization?

I study molecules weakly bound to nanoclusters and surfaces. During geometry optimization, I often run into problems like for example a small metal cluster behave nicely and has a given, stable ...
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10 votes
2 answers
349 views

How to calculate DFT energy with density from another level of theory?

I need to calculate the DFT energy given the density of another level of theory, for example Hartree Fock. $E[\rho_{HF}]$ This is sometimes used to fix various electron delocalization errors in ...
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8 votes
1 answer
410 views

How to get the .47 file from ORCA for natural bonding orbital analysis

I am trying to perform NBO analysis with relaxed density matrix with the open-source program JANPA. I am following the guide here. The first step is to get the NBO input .47 file from Orca v4.2.1. The ...
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9 votes
2 answers
630 views

What are Pair Natural Orbitals?

Recently, I came across electron correlation methods that use local pair natural orbitals (LPNOs) or domain-based local pair natural orbitals (DLPNO), such as DLPNO-MP2, DLPNO-CCSD etc. The dynamic ...
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24 votes
2 answers
549 views

Is it right to neglect very small imaginary frequencies?

I'm running a DFT optimization (B3LYP/def2-TZVP) and frequencies in ORCA for a molecule. And I get one or two very small (1-6 cm^-1) imaginary frequencies which corresponds to a slight bend of the ...
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7 votes
1 answer
247 views

Adding external electric field in ORCA with specific strength

Can anybody share methods to apply an external Electric field in ORCA? thanks!
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11 votes
1 answer
477 views

How do you calculate the change in dipole moment from ground to first excited state using ORCA?

How do you calculate the change in dipole moment from the ground to first excited state using ORCA? I have done DFT to get the dipole moment at the ground state and TDDFT of this neutral molecule. How ...
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11 votes
2 answers
529 views

Analytic gradient for DLPNO-CCSD

Is there a formula for analytical gradients (for geometry optimization) for the DLPNO-CCSD method? I ask because I know that it is not implemented in ORCA. Maybe PNO-CCSD is implemented in MRCC or ...
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11 votes
0 answers
189 views

I ran TDDFT on some small molecules. For some files, the ORCA output files cut short and contain no absorption data. What could be the reason? [closed]

Below is just the end of the output file, and the top of the input file. This is for the molecule FDICTF. The calculation did not run out of time. I ran a batch of 15 molecules, all with same ...
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5 votes
2 answers
114 views

For software that does not support FCIDUMP format, what format is used and how can we get the software to interact with FCIDUMP integrals?

Complementary to this question: How do the various programs read or write integrals in FCIDUMP format? which attempts to list all electronic structure packages that support the ...
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4 votes
1 answer
43 views

Defining coordinates using Vector3

I am trying to implement a tether restraint in the MM region of my QM/MM calculation using pDynamo (CHARMM/ORCA interface). I need to define the origin as a Vector3. Does anyone know how to do this?
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10 votes
1 answer
76 views

Constraining a set of atoms in the MM region using pDynamo (CHARMM/ORCA interface)

I am trying to perform a QM/MM optimization in which my substrate is in the MM region. However when this happens there are significant changes to the geometry (undesired). I want to avoid fixing all ...
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7 votes
1 answer
65 views

How to localize orbitals in pDynamo (CHARMM/ORCA interface)?

Does anyone know how to localize orbitals in pDynamo (CHARMM/ORCA interface). I am trying to identify the correct orbitals to swap for my high-spin iron(IV) system.
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9 votes
1 answer
100 views

How to swap orbitals in ORCA?

I am trying to swap orbitals for a high-spin iron(IV) complex. The orbitals that correspond to the iron are not in any of the SOMOs. I am using the pDynamo QM/MM program, which is an interface for ...
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20 votes
3 answers
316 views

What is the largest system that has been studied by the coupled cluster method?

This is parallel to the analogous question about the largest DFT calculation: What is the largest material that has been studied using density functional theory? I assume we allow high performance ...
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