Questions tagged [orbitals]

For questions about properties and types of orbitals

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0answers
63 views

Predict the density of states (DOS) diagram for rhenium oxide (ReO3) from the molecular orbital diagram

Yesterday I made this query on Chemistry Stack Exchange, and a user has felt that perhaps here I will get a quicker answer. The structure of rhenium(VI) oxide, $\ce{ReO3}$, is similar to that of ...
8
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2answers
224 views

Is the number of basis functions same in the different atoms in the 6-31G basis set?

I'm now studying the quantum chemistry calculation and Gaussian basis set. For example, when using the 6-31G basis set, the C atom has 6 basis functions in 1s orbital: 3+1=4 in $2s$, 3+1=4 in $2p_x$, ...
11
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2answers
135 views

Critical difference and roles of Slater- and Gaussian-type orbitals

I was very interested in the following question and answer about the Slater- and Gaussian-type orbitals (STO and GTO) used in quantum chemistry and a practical calculation. Gaussian-type orbitals vs ...
13
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1answer
213 views

How to calculate and plot localised orbitals with xTB?

The question is similar to How to calculate/plot molecular orbitals with XTB? Hence we can produce molden files from xTB calculations, which include the molecular orbitals. How do I proceed to get ...
6
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0answers
72 views

Is there a software package to analyse interactions in crystals?

I have been using Quantum ESPRESSO, specifically the pp.x module to study interactions via charge density plots. The process is slow as for crystals containing ...
5
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0answers
40 views

Kinetic energy cut-off for Gaussian-type orbitals when applying periodic boundary conditions [duplicate]

I have a solid with PBC (periodic boundary conditions) and I want to perform a DFT simulation. I use GTO as the basis. In a paper I read, I can transform the GTO to a Bloch function (crystalline ...
9
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1answer
240 views

How can I implement the Cartesian harmonics?

I'm studying the quantum chemistry calculation and now trying to implement the basic methods. For example, given a water molecule, $M = {(\ce{O}, R_\ce{O}), (\ce{H}, R_\ce{H}), (\ce{H}, R_\ce{H})}$, ...
14
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1answer
282 views

Gaussian-type orbitals vs Slater-type orbitals in terms of computational efficiency

When creating molecular orbitals via the linear combination of atomic orbitals method I am told that Slater orbitals provide a more accurate representation whilst Gaussian orbitals are computationally ...
4
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0answers
58 views

How can I calculate and plot the Molecular orbitals (MO's) from the Gaussian wavefunction file?

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 ...
7
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1answer
75 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 : ...
8
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1answer
146 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 ...
9
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1answer
155 views

How are molecular orbitals constructed from the coefficients and basis set?

When an SCF calculation is done in a QM program, the MO coefficients of the solution are printed into the output. Now, graphical softwares can plot 3D molecular orbitals from these coefficients, ...
7
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1answer
120 views

How to calculate/plot molecular orbitals with XTB?

I started playing with the XTB program (XTB is developed by Prof. Grimme group's, is based on tight binding and uses the GFN force field). Question: How can I calculate/plot the molecular orbitals? I ...
11
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1answer
100 views

Is there any relation between static correlation and finite-temperature smearing?

I am new to this field, so there is a chance that I am mixing two entirely different concepts together, but it seems to be that static correlation and finite-temperature smearing in DFT are somehow ...
6
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0answers
71 views

Unresolvable inconsistency between charge and multiplicity and orbital occupancies. Error while Distance Scan [closed]

I get the message mentioned in the title after a distance scan with a Gaussian calculation. I have bound a gold atom to a carbon in the pyridine ring and now pull this further and further out with a ...
15
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2answers
108 views

What is the difference between orbital localisation and NBO?

I am new to computational chemistry, I have used mainly GAMESS and Orca. In GAMESS, there are orbital localisation schemes like Pipek-Mezey, Ruedenberg-Edminston, etc. which generate orbitals that ...
10
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1answer
172 views

How to interpret molden AO/MO coefficients?

A simple calculation with Molpro 2012 on H2 molecule in cc-pvtz basis produces a molden file with 28 molecular orbitals. Each MO is defined with 30 AO/MO coefficient, but the number of symmetric AOs ...
11
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5answers
634 views

Plotting of natural bond orbitals (NBOs)

Which quantum chemistry programs can compute natural bond orbitals (NBOs)? Which visualisation tools can I use subsequently to plot pictures of the NBOs?