Questions tagged [atomic-physics]

Questions about atomic physics.

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6 votes
1 answer
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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 ...
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9 votes
1 answer
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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 ...
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13 votes
1 answer
264 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 ...
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6 votes
0 answers
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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 ...
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10 votes
2 answers
99 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 ...
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9 votes
1 answer
409 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....
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28 votes
1 answer
508 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 ...
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