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Questions tagged [gaussian]

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4 votes
1 answer
46 views

How to use rigid scan with dummy atoms in gaussian?

I am trying to use rigid scan using gaussian 09. In my case, there are three water molecules and I have placed a dummy atom at the centroid of the three water molecules. For simplicity, I want to ...
2 votes
0 answers
41 views

Calculation of dipole moment from gaussian

I am trying to calculate the dipole moment of water molecule using Gaussian16. The problem I face is the use of Density=Current keyword in the route section. Here is the input file and output file ...
3 votes
0 answers
39 views

How to compute molar Gibbs free energy (chemical potential) for single molecule using gaussian09?

I want to calculate the Gibbs free energy of single gas molecule (AsH3) using Gaussian 09, but I am confused between "Thermal correction to Gibbs Free Energy" and "Sum of electronic and ...
13 votes
2 answers
328 views

How to generate accurate displacements along normal modes?

How can i displace my structure along a particular normal mode, without coupling to other modes ? Rather than a exact mathematical procedure, I am more interested in a software/script/package that can ...
4 votes
0 answers
49 views

May I change the ICntrl variable in Gaussian 16?

Ive been trying to do energy calculations under the influence of a perturbative field with the BLYP and B3LYP functionals. Using the following input files: BLYP: ...
1 vote
0 answers
22 views

Optimization error in quantum dot graphene doping with antimony atoms

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2 votes
0 answers
24 views

Why am I getting wrong information about basis functions on running gaussian calculation using the 6-31G basis set for the krypton atom?

This is the information about basis functions which I am getting on doing Gaussian calculation. But according to the best of my knowledge Kr has six primitive Gaussians for 1s, 2s,2p, 3s, and 3p ...
4 votes
0 answers
21 views

bandstructure calculation of two-dimensional ferrovalley (RuClBr) in quantum espresso

We try to calculate bandstructure of single layer RuClBr reported in fig.4 of 'https://pubs.rsc.org/en/content/articlelanding/2016/pq/d3nr00346a/unauth'. But our obtained bandstructure is not similar ...
4 votes
1 answer
157 views

Can we build two graphite sheets as an input file in Gaussian?

I want to optimize a system containing a metal ion in between two graphite sheets. For that can I use Gaussian software? If so how can I create the input file with two graphite sheets?
1 vote
1 answer
117 views

Why is this geometry optimization in Gaussian not working for a system containing an amino acid, a water molecule and a metal (Pb) ion?

I started optimising a system containing amino acid residue, water molecule and a toxic metal ion, in proving a supposed reaction steps that might take place in inhibiting enzyme activity. The ...
3 votes
3 answers
179 views

GAUSSIAN 16 Error with CCSD(T)

My input file is: ...
5 votes
1 answer
190 views

Calculation of S1 energy in Gaussian

I am trying to calculate the energy of the S1 state with UDFT in Gaussian software. I understand that, generally, one should manipulate the charge and spin multiplicity to manually change the ...
4 votes
0 answers
91 views

Can I run Gaussian on Google Collab

Can I use Google Collab to run my Gaussian calculations? Due to the lower specification of my system, I can not run my calculations. I have to generate .wfn file. Is there any other idea or ...
2 votes
1 answer
341 views

'The combination of multiplicity electrons is impossible' in Gaussian

I am trying to calculate the energies of the S1 and T1 states of a molecule with UDFT using Gaussian. For the T1 state, I can successfully use the following input file: ...
5 votes
1 answer
165 views

What is the problem in my gaussian input?

I want to obtain the single point energy of a Ni-complex molecule, with a mixed basis set using the Gen keyword. The input is: ...
2 votes
0 answers
23 views

Are there any good tutorials on SHARC-Gaussian interface?

I am an aspiring quantum chemist planning on trying out the SHARC approach to study excited state proton transfer dynamics of organic molecules. I am comfortable with Gaussian 16 as that is the ...
4 votes
0 answers
53 views

Struggling with Mixed Basis Set Inclusion for IRC Calculations

I'm trying to compute the IRC for a W complex, and I'm using Def2TZVP for W and 6-311G** for the rest of the atoms. However, when I include the mixed basis set, Gaussian 16 generates a syntax error. I ...
2 votes
0 answers
23 views

How to seperate structures in bulk with connectivity from a relaxed scan in Gaussian 16?

I aim is to construct the PES for a molecule considering a specific bond length as the scan coordinate. I am using the Relaxed-Scan feature of Gaussian 16 for this using the ...
5 votes
2 answers
166 views

Trying to get concurrent results for a TDDFT calculation in Gaussian and ORCA

I am trying to do a simple TDDFT calculation in both Gaussian and ORCA from the exact same reference Geometry. I am using the same functional (making sure to use ...
2 votes
0 answers
77 views

Frequency calculation using Quantum Espresso

I want to calculate the frequency using quantum espresso. How can I get the input file of frequency calculation using QE? ...
8 votes
1 answer
748 views

Restart potential energy scan in Gaussian with additional scan points

I have finished a scan of a bond length, but I need to continue the coordinate scan adding more points to the same scan. I thought of writing a second input file from the last geometry, relaunching ...
2 votes
0 answers
17 views

Can I define molecular units on NBO3.1 or NBO6.0?

I'm studying donor-acceptor charge transfer (CT) process between tetrakis(m2-acetato)-di-Wolframium (acceptor) with an acetonitrile (donor) at the B3LYP-D3BJ/def2-TZVPD level of theory. The W···N ...
3 votes
1 answer
296 views

Singlet excited state optimization gaussian issue

I hope someone here can help me with some TD-DFT calculations. I am trying to calculate the excited state optimised structures and energies of some Germanium compounds. Firstly, I run a TD calculation ...
5 votes
2 answers
267 views

Gaussian 16: Relaxed scan using Jacobi coordinates expressed using generalized internal coordinates

For teaching porpouses, I would like to make a relaxed scan for an A-BC system (for example, the isomerization of of H-NC to H-CN or CH3-NC to CH3-CN) with Gaussian 16 using generalized internal ...
3 votes
1 answer
155 views

Difference in energy between first excited singlet and first excited triplet with DFT in Gaussian

I want to ask a further question related to this one. I have performed the calculations as explained and obtained a difference in energy of 0.71eV with the TDA-DFT level of theory. Then, I tried to do ...
4 votes
1 answer
377 views

Methologies to calculate excited states in Gaussian

Referring to previous questions asked here, I would like to pose a more general question about the calculation of ΔE(S1-T1) for organic molecules with the software Gaussian16. In particular, I have ...
5 votes
1 answer
324 views

S1-T1 energy difference in Gaussian

I would like to calculate the energy difference between the first excited singlet and the first excited triplet of a given molecule in solvent, on Gaussian. In this publication, they state that using ...
3 votes
0 answers
30 views

Constrained geometry optmization: Molecule interacts with its surroundings

I have a water cluster(suppose) generated from MD run. Now, I want to optimize the geometry of only one water molecule of interest using QC methods (e.g. B3LYP/6-31+G(d,p)). I intend that the water ...
4 votes
1 answer
51 views

Is it possible to find H-bond enrgy with O-H distance less than 0.95A?

I am trying to calculate the energy of a hydrogen bond between RCOO- and Tyrosine (figure below). I freeze the O-O bond at 2.8A and calculate the energy by changing the distance between O-H. But when ...
5 votes
1 answer
64 views

Is it possible to predict reduction reaction products with a Gaussian program?

In a molecular geometry calculation using a Gaussian program, can I see changes in bond lengths or changes in structure when one electron enters the molecule through a reduction reaction? for example, ...
3 votes
0 answers
177 views

Advise in generating ESP surfaces from Gaussian .cube files using the IQmol software

I am trying to generate an ESP surface of a Gaussian09 calculation using the iqmol software. I have used Gaussview to visualize the ESP surface by generating .cube files from .fchk files (using the ...
8 votes
2 answers
3k views

Emission and absorption UV-Visible spectrum using GAUSSIAN-09

I am currently studying the UV-visible spectrum of ethylene using GAUSSIAN-09. I optimized the ground state(# opt b3lyp/6-31g geom=connectivity) then used the ...
3 votes
0 answers
110 views

Error in output in gaussian [closed]

I am beginner regarding the use of Gaussian. Currently, i am trying to study the vibration of HgCl2. I have an error: Error termination via Lnk1e in /nfs/opt/Gaussian/16.c01/avx2/l301.exe Any help is ...
9 votes
0 answers
115 views

How does the line search in geometry optimisations work?

I am trying to write a Newton-Raphson geometry optimisation script in python (Current version of my code) using the energy, gradient and Hessian from Gaussian 16. In order to reach a minimum, I would ...
7 votes
1 answer
127 views

How many non-redundant internal coordinates are needed for optimisation of linear molecule?

I have been working to implement optimisation in internal coordinates (for a transition state search software I am working on). However, the implementation details are almost always glossed over in ...
5 votes
1 answer
287 views

How is the dipole moment defined in Gaussian?

I wonder if the origin of the permanent dipole moment calculated by Gaussian (16) is always the center of mass (0,0,0 if "Nosymm is used)? For the neutral molecule it does not matter, but I am ...
2 votes
0 answers
55 views

how to calculate the total charge for a specific fragment in a molecule using NBO analysis with Gaussian? [closed]

hi my molecule is devided into 5 fragment, I want to perform an NBO analysis and calculate the total charge of each fragment instead of doing it by hand (by summing atomic charges) , is there a way to ...
2 votes
0 answers
45 views

How much should you shift fragment energies to create an energy level diagram?

I am creating an energy level diagram for the orbitals of [XeF₅] - molecule produced by two fragments: [Xe] 4+ and [F₅] 5-. There is a very large energy difference between the two fragments, so I ...
3 votes
1 answer
264 views

Comparison between the ordering of Molecular Orbital coefficients between Gaussian and PySCF

I am trying to compare the Molecular Orbital coefficients obtained from PySCF and G09 program. Below is the PySCF and Gaussian input and output. I am using 3-21G basis and RHF method for both the ...
3 votes
1 answer
151 views

How is the LUMO lower energy than the HOMO for triplet state restricted-open shell DFT calculation?

I recently ran a calculation using the ROB3LYP/LANL2DZ level of theory for a triplet spin molecule. While analyzing the results, the HOMO is doubly degenerate and the LUMO is singly degenerate. I ...
2 votes
0 answers
73 views

Help setting the input geometry into standard orientation for a single point g09 calculation

I am trying to run a single point g09 calculation for a pentagonal planar molecule with D5h symmetry using the B3LYP/LANL2DZ level or theory. I would like the calculation to use symmetry, however the ...
3 votes
1 answer
334 views

Advice on converging a restricted open-shell DFT (rob3lyp/LANL2DZ) single point Gaussian09 calculation for a triplet spin-state molecule?

I am running a single point calculation on a fragment of a molecule using restricted open-shell theory. The fragment is in the triplet spin-state and of pentagonal planar structure (D5h). I ran the ...
1 vote
0 answers
73 views

Fluorescence solvated band shape in Gaussian16

I am trying to calculate the fluorescence spectra in solvent with Gaussian16. I followed the example reported here to calculate the value of the vertical emission. However, in the same link, I read: ...
3 votes
0 answers
66 views

How to choose the orientation of basis functions in a Gaussian calculation?

I am trying to run a g09 calculation for a D5h symmetric molecule using the HF/LANL2DZ level of theory. The molecule is pentagonal planar in geometry, and I would like to visualize the canonical ...
5 votes
1 answer
85 views

Using Hindered Rotor Scans With Different Convergence Criteria from Gaussian

I am having trouble with a difficult convergence in Gaussian16. I am running two separate PES scans for hindered rotors in my molecule that will eventually be used in subsequent rate calculations. I ...
4 votes
2 answers
105 views

Cannot optimize hexa aqua Cu(II) and Fe(III)

I try to optimize very simple systems - hexa aqua Cu(II) and hexa aqua Fe(III) - in Gaussian 16. The inputs are provided in the end of the post. Unfortunately, the geometry optimization never finishes ...
2 votes
1 answer
105 views

using the gen function in gaussian

I'm trying to optimize a structure that contains Pd atom with the gen function on gaussian16 ...
4 votes
1 answer
467 views

Frequency run does not converge in Gaussian16

I have been optimizing some particularly tricky structures with Gaussian. The optimizations end well and they don't have negative frequencies. However, when checking the convergence of the frequency ...
8 votes
2 answers
681 views

How do I interpret the Gaussian16 wavefunction file?

I'm new to gaussian16. The wave function file that I obtain as a result of the "Energy" calculation. It consists of five distinct parts : PART 1 : ...
5 votes
1 answer
453 views

Convergence problem in geometry optimization in Gaussian16

I have a quite big set of molecules to optimize and study and, after some research in the literature, I selected B3LYP/6-311G* level of theory. These molecules are quite big and wobbly, so I expected ...