Questions tagged [pauli-exclusion-principle]

The Pauli exclusion principle states that two identical fermions, (so with half-integer spin) cannot occupy the same quantum state simultaneously, and thus share all of their quantum numbers. Also use for structure and classification schemes involving antisymmetry.

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Why there aren't classical field associated with fermions?

In A Introduction to Nuclear Physics by GreenWood, It's written Bosons are particles that obey Bose-Einstein statistics and are characterized by the property that any number of particles may be ...
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Ground state energy for fermions with different spin orientation [closed]

Electrons are subject to a harmonic potential in one dimension, described by one-particle Hamiltonian $$H = \frac{P^2}{2m}+\frac{1}{2}m\omega X^2,$$ where $P$ are the momentum operator, $X$, is the ...
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Fermions and Pauli Exclusion Principle

I started to study quantum ideal gas and I am reading Salinas "Introduction to Statistical Physics". In chapter 8 , he states that when speaking of fermions, only one particle can occupy an ...
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Why is a 2-electron wavefunction antisymmetric? [closed]

Why does a 2-electron system have an antisymmetric wavefunction when the combination should be bosonic? I.e. If it's an overall bosonic combination, shouldn't the overall wavefunction be symmetric?
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Don't the four quantum numbers make two electrons distinguishable?

From the Pauli's Exclusion Principle no two electrons in a bound system have all same quantum numbers. This means that an electron can be uniquely specified by the four quantum numbers and hence can ...
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Pauli principle for semiclassical electrons

In the discussion of electrons in metals, often the semiclassical model is used. There, the electrons are treated as occupying localized wave packets $|k,x_i\rangle$ which have momentum $k$ and ...
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Probability of two electrons of different energy levels contained in a single infinite potential well being found in same region

What is the probability of two electrons in a single infinite potential well centered at 0, one in the ground state, the other in the first excited state, being in the same region? I know by the Pauli ...
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Why we can stand on the floor? [duplicate]

Feynman (Volume 1, 38-4) seems to explain the normal force of a floor acting on a table as quantum mechanical, arising from the Pauli Exclusion Principle and also, the Heisenberg Uncertainty Principle....
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About the vanishing of the totally antisymmetric entangled spin-triplet wavefunction when all quantum numbers are different

Consider the totally antisymmetric entangled spin-triplet wavefunction $$\psi=\left(\psi_\alpha({\vec r}_1)\psi_\beta(\vec{r}_2)-\psi_\alpha({\vec r}_2)\psi_\beta({\vec r}_1)\right)\left(|\uparrow_1\...
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How far does the Pauli Exclusion Principle go?

I am reading a paper on Neutron Degeneracy (http://www.physics.drexel.edu/~bob/Term_Reports/John_Timlin.pdf) and it is discussing the Pauli Exclusion Principle. There has to be trillions and ...
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Pauli Exclusion Princple for a fermion and antifermion

I understand that the Pauli Exclusion Principle applies only for identical particles, so that a fermion and an anti-fermion should be allowed to be in the same state. However, when I look at the ...
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Does the Pauli exclusion principle apply to one fermion and one antifermion?

I understand that two fermions cannot simultaneously have the same <momentum, spin> state. I know this is also true of two anti-fermions. But is it possible for one fermion and one anti-fermion ...
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Why is the Pauli exclusion principle not considered a sixth force of nature?

Why is the Pauli exclusion principle not considered a sixth force of nature, given it produces such things as repelling of atoms and molecules in solids?
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How is Pauli's exclusion principle conserved in transformations from real space to $k$ space for a Fock space hopping Hamiltonian?

$$\hat{H}= -t\sum_{\langle i,j\rangle} c_{i\sigma}^{+}c_{j\sigma}+h.c$$ For this Hamiltonian a lattice with all sites doubly occupied would give 0 in real space and for single occupancy it gives $-4t^{...
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Can a particle have multiple spin states at the same time?

In quantum mechanics, particles are described as wave-like. This means, for example, that an electron or photon does not have a well-defined position before one measures it and causes the wavefunction ...
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Pauli exclusion principle for $H_{2}$

We know that depending on whether their spins are parallel or antiparallel, two electrons (each with spin ½) can combine to give a total spin of $1$ (parallel)or $0$ (antiparallel). But only one of ...
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Generalization of the Pauli principle

A generalization of the Pauli principle has been studied a reference here , and the generalization offers a way to study the wave function with more detail for "n" particles- say electrons ...
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What would happen if the Pauli exclusion principle did not exist?

There can be never two fermions in exactly the same state, which is known as Pauli’s exclusion principle, but infinitely many bosons. I read in the book saying that if Pauli's exclusion principle does ...
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Does degenerate matter have anything to do with the degeneracy of eigenvalues and eigenstates?

I came across degenerate matter (not the first time) after learning about degeneracy in eigenstates and eigenvalues. Are the two connected? Or is this just another use for the term?
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Pauli Exclusion principle: Query

The definition that I have concluded is that: No two fermions can exist in the state, or quantum state, unless they have opposite spins. Am I right in saying this? They can have the same azimuthal ...
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Can why electrons exist in shells be explained by the Pauli exclusion principle?

Do you know the Pauli exclusion principle?-'No two particles could be in the same quantum state at once'. Well can you use that principle to explain why electrons stay in shells and electrons in ...
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Can indistinguishable particle wavefunctions be written as a product of total observable eigenstates?

Consider the wavefunction of say two electrons in an external potential, associated with two possible states $\phi_a$ and $\phi_b$. Furthermore, each electron can have two spin states $\chi_1$ and $\...
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Virtual fermions vs exclusion principle

How QED eliminates the cases when in loop corrections two fermions get created with the same momenta and spin state? Is it done by the ladder operators? Edit: the two fermions are in two distinct ...
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Experimental evidence of Pauli principle for non-bound fermions

I mean electrons in atoms/molecules/solid bodies not count here. I heared of an experiment measuring the degeneracy pressure of a fermion gas.
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What happens if I replace an electron in a $\rm Li$ atom by a muon?

According to my knowledge the exclusion principle won't affect it, so it will jump to the muonic 1s orbit (strongly deformed by the electrons' repulsion). The electrons fill the electron 1s orbits (...
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Why is the wavefunction of a mixed-flavor baryon (e.g. the proton) antisimmetric under exchange of quarks of different flavors?

A similar question has been put before in this forum, but not with full clarity. So I would like to revisit the question and express it differently, hoping for a crystal clear answer. The question is: ...
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Could the Fermi statistic be a force?

I'm aware that, according to the Pauli principle, identical fermions obey the Fermi-Dirac statistics, so they don't occupy the same state because they just can't, it's simply how they behave. I'm ...
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Can multiple Helium-4 nuclei occupy the same place because the nuclei are bosonic?

A quarter of all matter in the observable universe is Helium-4 while all Helium-4 atoms have a nucleus with a zero spin integer which is characterized by Bose–Einstein statistics. Does this mean that ...
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Exchange Symmetry of Spatial Wave Functions in case of two Electrons and the Pauli Principle

I have some problems understanding the symmetry of spatial wave functions. In my experimental physics course they tought us that in atoms the total wave function $\Psi_{tot}(\vec{r}_1,\vec{r}_2)=\Psi(\...
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Why would one think that a solution of the time-independent Schrödinger equation is in the span of configuration state functions?

I am trying to understand why the hypothesis of configuration interaction methods is valid, i.e. I want to understand why one would think that an $N$-body wave function would be in the span of ...
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Pauli principle and Schrödinger/Pauli equations

In quantum mechanics state of the system is determined by wave function, which evolves according to the Schroedinger equation, or by Pauli/Dirac equation which are derived from Schroedinger equation ...
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Wave equation for two Fermions

I came across this basic exercise but I don't fully get the gist of it. Consider two neutral particles in a 1D Box with the interval $0\leq x \leq L$. The interaction between the two particles is ...
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Pauli exclusion principle and quantum state

Wikipedia says that two identical fermions cannot occupy the same quantum state. My question is what this quantum state means? In classical mechanics, this means that the two particles cannot have the ...
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Spin-Spin Hamiltonian in coupled harmonic oscillator

I was reading about identical particles and i came across this example: Consider two electrons with spin 1/2. The Hamiltonian for this system is: $$Η=\frac{p_1^2}{2m}+\frac{p_2^2}{2m}+\frac{1}{2}m\...
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Is there a difference between boson and bosonic?

I read about Bose-Einstein condensate consist of bosonic atoms at incredible low temperature do not obey Pauli exclusion, I am wondering what happens if it is possible to create fermionic photon for ...
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Symmetry of fermion wavefunction

I'm studying identical particles and I'm thinking about something related to fermions. I have always heard that more than two electrons can't occupy the same energy level, because their spins are ...
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Anti-symmetric property of Fermionic wave function

I am reading Quantum Statistics from 'Fundamentals of Statistical and Thermal Physics' by Frederick Reif. I have questions in two places. I understand the following paragraph: Particles with half-...
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Compatibility of spectroscopic term values with Pauli Exclusion Principle

The ground electronic configuration of Carbon is $1s^2$$2s^2$$2p^2$ $l_1=1$ and $l_2=1$ $\implies$ $L=2,1,0$ $s_1 = \frac{1}{2}$ and $s_2=\frac{1}{2}$ $\implies S=1,0$ So the terms are $^{3}D,^{1}D,^...
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How Hund's rule 1 and rule 2 prevent double occupancy?

According to Hund's rule of filling up the orbitals, the ground state electronic configuration of Nitrogen is $1s^22s^22p_x^12p_y^12p_z^1$. The electrons first singly occupy the orbitals $2p_x, 2p_y$ ...
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How does the Pauli Exclusion principle explain the incompressibility of metals?

The Pauli Exclusion principles states that no two identical fermions can have the same quantum state. In my lecture notes, it is mentioned that this principle helps us explain the fact that metals are ...
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Relation between isospin invariance and charge independence

I don't know if this question is better suited for this forum or math.stackexchange.com. I come from a mathematical background and I'm struggling to understand a passage in Lipkin's book "Lie groups ...
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What is the range of Pauli's exclusion principle?

In many introductions to the pauli's exclusion principle, it only said that two identical fermions cannot be in the same quantum state, but it seems that there is no explanation of the range of those ...
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Is the position of an electron part of his quantum state? Pauli exclusion principle

I have a problem regarding the Pauli exclusion principle which as far as I understand states that two or more identical fermions cannot occupy the same quantum state. So is the position ($r_1$) of ...
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Is the Pauli Exclusion Principle the Cause of Normal Force? [duplicate]

I'm currently studying about Dynamics in my physics class. I was looking up where the normal force comes from, and I thought that the normal force comes from Newton's third law. However, going through ...
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How does Pauli's Exclusion Principle relate to a quantum superposition of states?

Pauli's Exclusion principle states 2 fermions can not occupy the same quantum state. However, a particle can occupy a superposition of quantum states. Does this mean you can have an infinite amount of ...
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What is the intuitive physical difference between fermions and hard-core bosons?

(This is a soft question.) If we work on a discrete lattice for simplicity, then ordinary bosons are characterized by creation and annihilation operators that satisfy the canonical commutation ...
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When two identical fermions exchange, the wavefunction changes sign. Then why the statement is no new state is created?

When two identical fermions exchange, the wavefunction changes sign. Then why the statement is no new state is created now that the wavefunction is changed?
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Some questions about Dirac's sea? [closed]

Did Paul Dirac develop some way to include bosons in his formulation of the sea of particles? I have read that both electrons and anti-electrons would follow the same Dirac equation. But could there ...
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Isobaric spin $T = 0$ and Pauli-exclusion principle

I was reading a Book of Nuclear Physics (Concepts of Nuclear Physics by Bernard L. Cohen), in which he discusses the concept of Isobaric spin T and defines it by saying We see that only wave ...
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Can two fermions occupy the same energy level on a harmonic potential? [closed]

Suppose that we have a harmonic potential $\hat{V}(\hat{X})=\frac{1}{2}k\hat{X}^2$ which we will, for simplicity, consider to be one dimensional. Now let's place two fermions within this potential, ...

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