Questions tagged [orca]
For questions about (or involving) the ORCA electronic-structure package.
36
questions
7
votes
1
answer
122
views
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 ...
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 ...
- 81
5
votes
2
answers
110
views
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.
...
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
...
- 357
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 ...
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
...
- 357
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 ...
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 ...
- 343
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 &...
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".
...
- 5,499
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 ...
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 ...
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:
...
- 343
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 ...
- 61
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 ...
- 9,801
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 ...
- 9,801
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,...
- 793
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) ...
- 365
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 ...
- 73
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 ...
- 1,551
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 ...
- 1,638
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 ...
- 7,744
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 ...
- 5,499
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 ...
- 5,499
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 ...
- 2,293
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!
- 71
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 ...
- 331
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 ...
- 3,629
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 ...
- 331
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 ...
- 27.8k
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?
- 1,486
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 ...
- 1,486
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.
- 1,486
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 ...
- 1,486
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 ...
- 3,629