Questions tagged [orbitals]
For questions about properties and types of orbitals
18
questions
5
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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?
