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Questions tagged [gaussian]

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35 votes
5 answers
10k views

What is a good replacement for Gaussian?

When I started studying computational chemistry (circa 2007), my supervisor used to tell me about the controversy surrounding Gaussian, Inc. regarding the banning of researchers involved in the ...
1__'s user avatar
  • 513
6 votes
1 answer
563 views

Can a file in the Gaussian CUBE format be voxelized?

My aim is to voxelize a CHGCAR file. I am trying to build up a workflow to do the same. With the aid of the Matter Modeling community members, I have figured out a way to convert a CHGCAR file into ...
Pranoy Ray's user avatar
  • 1,637
19 votes
1 answer
536 views

Retrieving Translational and Rotational Modes

I'm doing some post-processing using the vibrational modes of a molecule to solve a linear system of equations, but I believe I need all the modes in order to have a single, well-determined solution. ...
Tyberius's user avatar
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18 votes
1 answer
188 views

Discrepancy between numerical and transformed derivatives

This is related to a prior question of mine Derivatives with respect to user defined vibrational modes. While that one focuses on potential software to use for derivatives with respect to normal modes,...
Tyberius's user avatar
  • 15.6k
15 votes
2 answers
894 views

What are the parameters that need to be calculated to design the structure of a molecule?

Before performing Molecular Dynamics on a co-polymer that doesn't have a ready-to-use structure anywhere, the monomer fragment was built in Avogadro software with 0 net charge, B3LYP theory and 6-31G(...
Kavya Mrudula's user avatar
10 votes
4 answers
2k views

How can I find the parameters in a basis set?

I have a question about the basis functions of Gaussian. When the basis function is set (e.g., 6-31G), I would like to know the specific value of Gaussian's parameters for each atom. In particular, I ...
neco's user avatar
  • 1,789
9 votes
3 answers
1k views

Which software is good with generally contracted basis sets?

Recently, I learnt that basis sets can be contracted as segmented (like def2 or 6-31G) or general (like cc-PVTZ, or ANO). The general contraction allows all the primitives to appear in all shells, ...
S R Maiti's user avatar
  • 7,021
7 votes
1 answer
541 views

Transforming basis functions from Cartesian to speherical

I read the basis set from book A d-type GTO written in terms of the spherical functions has five components (Y2,2, Y2,1, Y2,0, Y2,1, Y2,2),but there appear to be six components in the Cartesian ...
Dompink's user avatar
  • 79
5 votes
1 answer
334 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 ...
Laura's user avatar
  • 1,267
13 votes
1 answer
3k views

How to plot a Gaussian cube file with python/matplotlib?

I know there are programs that can automatically visualize .cube files (like VMD), but I'm trying to do it myself in python/matplotlib (or equivalent) to better understand what the numbers mean. I ...
johnymm's user avatar
  • 231
12 votes
3 answers
608 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) ...
Alex I's user avatar
  • 1,038
11 votes
1 answer
401 views

Calculate Redox Potential

I am interested in calculating some redox potentials of organic compounds (H,C,N,O,F,Cl,Br) in organic solvents such as MeCN. I do not need absolute agreement with experiments since this is just a ...
Tristan Maxson's user avatar
10 votes
4 answers
2k views

Codes for post-processing Gaussian cube files?

I have generated MOs of a molecular system and I need to recreate its electronic density via $\rho(r)=\sum_{A_i}|\psi_i(\mathbf{r})|^2$ where $A$ is a set of occupied MOs. I am trying to do this via ...
mykd's user avatar
  • 2,342
9 votes
1 answer
826 views

Is it possible to do TD-DFT/6-31G+(d,p) calculations on a laptop?

In the recent publication: "Density Functional Theory Calculation on the Structural, Electronic, and Optical Properties of Fluorene-Based Azo Compounds", the author claimed to have used ...
Protima Rani Paul's user avatar
8 votes
1 answer
238 views

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 ...
capitn96's user avatar
8 votes
2 answers
682 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 : ...
Atom's user avatar
  • 1,005
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 ...
S R Maiti's user avatar
  • 7,021
6 votes
3 answers
1k views

Units of energy in Gaussian

I want to calculate the redox potential for a molecule in water using Gaussian. I found a tutorial at 1, but I'm got confused about the units at the end. They have a result for the Gibbs Free Energy ...
Andrea's user avatar
  • 856
5 votes
0 answers
580 views

How can I calculate and plot the molecular orbitals (MO's) from the Gaussian wavefunction file? [closed]

This a follow-up question to my previous question. And as per the answer one could create M.O orbitals from the primitives. As a new user of Gaussian, is there any method (or algorithm) to followed so ...
Atom's user avatar
  • 1,005
3 votes
1 answer
765 views

A different way to optimize triplets?

I am studying a system with TD-DFT method implemented in Gaussian. I am not sure whether this two inputs are adequate by the mean of output - optimization of T1? ...
farmaceut's user avatar
  • 576
3 votes
0 answers
198 views

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 ...
PriZarah's user avatar
  • 409
3 votes
1 answer
800 views

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 ...
AlfredV's user avatar
  • 183