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Questions tagged [atomic-physics]

Questions about atomic physics.

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4 votes
1 answer
49 views

How to get 192 of CeO2 atoms coordinates using Vesta?

Here is the CIF file of CeO2 (http://www.crystallography.net/cod/1562989.html). One of the paper mentioned that they have used 192 CeO2 atoms constructed by 444 primitive cells. To generate the ...
0 votes
1 answer
44 views

In which irreducible representations shall I put the electrons in an F atom in PySCF?

I’m looking to complete ROHF energy calculations in PySCF for the F atom. I need to update the irrep_nelec dictionary for F. I know that the one for the O atom is: ...
9 votes
2 answers
2k views

Acceleration of 8110823001207866000 m/s^2 by using Coulomb's law: did I do it right?

I have this very simple function: ...
6 votes
1 answer
202 views

For one atom, what is the correct point group?

I have a concern related to the follwoing question When orbitals are labeled based on their irreps in D2h, how are the orbitals ordered for an N atom? In which the following Answer clearly states that ...
15 votes
2 answers
2k views

Why is my hydrogen energy not equal to -0.5 hartrees?

I'm trying to calculate the HOMO of various molecules in water solution. I first tried to see how PySCF calculates the HOMO of hydrogen. I ran the following code: ...
3 votes
0 answers
52 views

Beginning in molecular simulation world

I want to do a simulation of an atom (type atom is not important) bouncing inside a spherical surface (the material of the surface is not important too) (i.e. starting from an initial velocity, the ...
3 votes
0 answers
60 views

Are then any material property solvers (from Charge Density) available in python? [duplicate]

I am looking to predict properties like the Bulk Modulus, total energy, etc., all from the charge density I have as input (CHGCAR file)
4 votes
0 answers
100 views

Why are some point groups for single atoms listed as Oh in the CCCBDB?

Does anyone know why the CCCBDB database lists the tin cation and antimony atom as having the Oh point group (please see the screenshot below from CCCBDB when I look at "All molecules sorted by ...
1 vote
0 answers
35 views

How to find out electric field Intensity for a far distant point in COMSOL multi Physics [closed]

I have a surface plot for which I would like to find the E (Electric field intensity) at a far field point marked in red on the plot. Therefore I would like to calculate Ex and Ey, so that I can ...
2 votes
0 answers
137 views

Primitive Translation Vectors from Lattice Vectors (with varying Space Groups) [closed]

I am looking at some raw POSCAR data of some Primitive Cells, and I wonder how I can get a simplified directional representation of the lattice vectors. I have two examples: Example 1: ...
5 votes
1 answer
120 views

Finding the Configuration State Functions of Atoms

Is there a book or tabulated work where the configuration state functions of atoms have been documented? Just as useful would be information about computer programs that are able to predict the CSFs.
1 vote
0 answers
79 views

Gaussian(Software): What does atomic orbital contribution mean? [closed]

Example Molecule: C60 (Fullerene) Route Section: #p B3LYP/6-311G(d) guess = read geom = check pop = full Question: What information can I get from atomic orbital contributions? I've calculated atomic ...
7 votes
1 answer
388 views

Why can't DFT calculate the accurate electronic configuration of the Oxygen atom?

I am trying to do a DFT calculation of Oxygen atoms with the VASP code. My settings follow the official tutorial on the Oxygen atom of VASP. But it turns out the energy levels of the two spin ...
9 votes
1 answer
103 views

In which theoretical framework does the size of an atom depend on the temperature of the gas (Bose-Einstein condensates)

In order to pose the question, I reproduce an excerpt from this Physics.SE question, about the size of atoms in a Bose-Einstein condensate (BEC): Heisenberg's uncertainty principle in frames of ...
12 votes
1 answer
892 views

How to determine which levels correspond to each other in LS coupling and jj-coupling?

In the LS coupling scheme, L, S and J are good quantum numbers; whereas in jj-coupling scheme, j1, j2 and J are good quantum numbers. I have learnt how to get the term symbols for LS coupling, and for ...
6 votes
0 answers
43 views

Atomic Packing Fraction [closed]

I need to calculate excess entropy of mixing for a particular system of alloy. The excess entropy of mixing is dependent on temperature and it takes into account this temperature dependence by using ...
28 votes
1 answer
662 views

How accurate are the most accurate calculations?

Taking into account the fact that the theory of quantum gravity does not exist and the QED calculations are not possible for most realistic chemical systems, what levels of accuracy can we expect from ...
10 votes
2 answers
190 views

Quantifying electronic overlap?

I am trying to understand how to quantify the electronic interaction/conduction/overlap between two metal cores at varying distances. As someone who works primarily with classical MD, and has less ...
9 votes
1 answer
513 views

High precision helium energy

In the paper "High Precision Theory of Atomic Helium", Drake lists the then best-known ground state energy of the Schrödinger equation for helium to 22 digits as: $$\lambda_0 \approx -2....