Questions tagged [gaussian]
For questions related to the Gaussian electronic structure program
156
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Gaussian 18: 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 ...
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27
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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 ...
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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 ...
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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, ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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147
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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 ...
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74
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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 ...
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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 ...
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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:
...
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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 ...
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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 ...
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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 ...
user1441
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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 ...
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using the gen function in gaussian
I'm trying to optimize a structure that contains Pd atom with the gen function on gaussian16
...
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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 ...
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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 ...
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How can I specify different theory levels for different atoms in Gaussian?
I have a bunch of geometry optimisations I want to run for a cation Metal-organic complex. This is going to be a repeat of calculations that were done in "Turbomole" previously and my Prof. ...
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Frozen core Stability Calculations in G09?
I am trying to calculate the stability of CO at HF/3-21g level using G09. I am trying to reproduce an issue that was observed in PySCF, and I have made the following observations:
If I use the ...
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What is the procedure to calculate the vibrationally resolved UV-Vis spectrum in solvent with Gaussian?
I followed the tutorial reported here to calculate the vibrational resolved spectrum in vacuum. The spectrum seems ok and it is actually close to the experimental one.
However, I would like to add the ...
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How do you make sure the reaction is diffusion limited (Gaussian)?
I am investigating the mechanism of hydrogen transfer between a hydroperoxyl radical and an aromatic hydroxyl group donating it. The problem is that I cannot find transition state structure. So far, I'...
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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 ...
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Gaussian does not reproduce UV-Vis spectrum [closed]
I am performing some TD-DFT calculations to reproduce the UV-Vis spectrum of a molecule using Gaussian. After optimizing the structure, I performed a TD-DFT calculation with 150 states and I tried ...
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Computing the kinetic energy of a molecular orbital
I want to compute the kinetic energy of the molecular orbitals computed by Gaussian 09, the variable U in this paper. Can it be computed from the orbital energy using a formula or does it need to be ...
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How to calculate charge transfer (CT) in NBO Analysis using Gaussian 09?
I have a coronene structure, functionalized with hydroxyl groups.
I want to calculate the charge transfer (CT) between the coronene and the hydroxyl group, using NBO analysis as implemented in ...
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Compute polarizability after each step of relaxed scan in Gaussian 16
I am computing a relaxed 2D scan with Gaussian 16 in order to reproduce some computational data. I am interested in computing the dipole moment vector and the (static) polarizability matrix after each ...
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Scanning two bond lengths G-16
If a scan is performed over two CVs, or collective variables (bond lengths here), does the code simultaneously step through both of the CVs or does it step through the first one, and scan the second ...
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Computing the rotational entropy in RRHO approximation
I am implementing the computation of Gibbs energies by their molecular parameters (structure, frequencies) in my program Chemcraft (the main task is the possibility to cut small frequencies which ...
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Absorption spectra with Gaussian [closed]
I want to calculate the absorption spectra of molecules (and possibly ions) with TD-DFT.
I have used Gaussian in the past and, to my knowledge, the application of TD-DFT is implemented in this code. ...
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How to assign UV-vis maximum absorption wavelength theoretically by using td-DFT?
I'm currently working on the simulation of Uv-vis absorption spectra of some organic compounds, while performing TD-Dft the log file that we got contains the values of deltaE of the transition,...
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Gaussian enzyme optimization fails, possible memory error?
I started to optimise a selected cavity of the enzyme with a metal ion using Gaussian 09 software. The basis set used for C,H,N and O atoms was 6-311+G(d) and for the Cd2+ ion was def2-tzvp. And, ...
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Gaussian: Error termination just before the calculation ends [closed]
I am trying to optimize a cluster based structure using DFT. However, just before the calculation ends the gaussian give me an error termination without even specifying the cause of this error
...
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How to compute free energy for solvation using gaussian09?
I'm trying to compute the free energy of solvation of a molecule in gaussian09 using the continuum solvation model, but I am haveing difficulties, I don't know how to do it and gaussian manual does ...
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Perovskite Optimization does not converge using gaussian [closed]
I am trying to optimize the geometry of (C5H14N2)[CuCl4] using g09. However, the calculation is not converging at any level of theory in 250 cycles. I am new to this field and I think I have made a ...
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How to plot emission spectrum using gaussian?
I'm trying to learn how to plot emission spectrum for my system, but, as an initial test case, I'm trying to do this for methane.
I calculated the optimized geometry of the ground state, then I ...
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Calculating Te chemical shifts with Gaussian
I am trying to calculate chemical shifts for Tellurium in an organotellurium compound with Gaussian16 but the calculated values do not match experimental values at all. I know that NMR calculation ...
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Energy calculation with implicit solvation [closed]
I am trying to investigate a hydride transfer reaction of a transition-metal complex like the following:
$$
\ce{[M]-H + Ph3C+ -> [M]+ + Ph3CH}
$$
For this I want to investigate the influence of ...
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Gaussian crash while calculating vibrational frequencies for an organic molecule [closed]
I'm trying to run an opt+ freq calculation using B3LYP/Lanl2DZ for an organic molecule that contains 4 $\ce{CF3}$ groups, my gaussian suddenly crashed, so I did the calculation in two steps: first opt ...
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How can we restart an interrupted Gaussian job? [closed]
I started to optimise a protein. But due to a power failure the process terminated before completion. So I need to restart my calculation. There were several suggestions on using ...
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Is it necessary to give connectivity and charge of a molecule to start a Gaussian job?
Let's think we want to do a Gaussian optimisation. We first download the pdb coordinates of the query protein from the protein data bank. Then using Chimera software we add hydrogen and charge for the ...
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"Gview.exe" in Linux is not responding [closed]
I successfuly installed g16 and gview6 under fedora linux , the issue that I have is when I open gview after few seconds it stopped and a message is displayed on my screen
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maxstep Gaussian keywords
I'm running a Berny optimization and I need to include the keyword maxstep=1.
Observing the output, in the convergence summary table I can see that the ...
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problem with the installation of g16 with gaussview under Linux
I don't know how to install the g16 with gv under Linux. According to the internet the installation seems to require a file called a tar.gz which I don't find in the g16 folder. I have a lot of files ...
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Gaussian error in optimization [closed]
I want to optimize an enzyme in the presence of a metal ion.
I started the optimization for the system in the ground state with DFT (B3LYP) method using 6-31G(d) basis set.
But, this gave an error
<...
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