Pauli Definition and 229 Threads

As far as I am aware, Pauli Paramagnetism applies to electrons in bands while Curie Paramagnetism applies to localised electrons. Pauli Paramagnetism is usually much weaker because only the electrons near the Fermi Surface can change its spin to align with the magnetic field. On the other hand...

How is it that only 1 spin up and 1 spin down electron are allowed in an atom even though there is no measurement to collapse the state function?

Why is norm of (pauli matrix)/sqrt(2)=1

The way I understand Pauli exclusion principle is: no two electrons can be of the same quantum state in an atom. But electrons from two atoms of the same element, let’s say hydrogen for simplicity, are in the same quantum state, is that right? That is what distinguished it from helium for...

Good evening. I have been reading that the repulsion generated by the Pauli exclusion principle barely prevents neutrons in neutron stars from occupying the same quantum states (after all, they are fermions). However, the principle seems to be violated in a black hole, given that fermions are...

Homework Statement How would the world change if there were no Pauli exclusion principle? Specifically, how would the band theory of metals change? a) Assume you had a small copper coin of mass 3.12 grams. How much energy would be released from the coin if the Pauli exclusion principle were...

Homework Statement Show that the inner product of the Pauli matrices, σ, and the momentum operator, \vec{p}, is given by: σ \cdot \vec{p} = \frac{1}{r^{2}} (σ \cdot \vec{r} )(\frac{\hbar}{i} r \frac{\partial}{\partial r} + iσ \cdot \vec{L}), where \vec{L} is the angular momentum operator and...

In the same way we could create "principles" for the other forces which would not make them not forces. Is it a misunderstanding of the meaning of a force or principle? Could someone clarify this for me.

Hello! From what I have understood, there are two different states that an electron can have (Spin up and spin down), and if two electrons are in the same state their wavefunction collapse. So far so good. In a video I saw, they claimed that because of this, only two electrons can exist in the...

This question might be beyond our current knowledge but i want to make sure. The reason why fermions do not overlap is due to the pauli exclusion principle which states that one fermion cannot occupy the same state as another fermion. a quark is 10-18m and a proton is 10-15m, 3 orders of...

Fermions are well known for NOT being able to exist in the same state, whereas bosons can. Hence why once an S orbital in an atom has two electrons (with opposite spins), that's it. But I've only ever seen this discussed for a single type of particle at a time. For instance, could a muon...

What the heck is meant by "Pauli force/effect"? I'm a last year physics undergrad and whenever I have a physics class given by an experimental physicist (e.g. solid state physics), they sometimes say things like "... and because of the Pauli force these two electrons are repelled ..." and...

According to Pauli principle, it is impossible for two electrons in the electron gas to have the same state. on the other hand, we say that each spatial state can be filled by two electrons with opposite spins. But my question; Suppose we have two electrons, one spin down and another spin up...

According to Slater determinant, can one say that two bosons are able to place in the same position X , but two fermions can not, no matter what their states are?

I understand that there may be no answer to the question "Why is Pauli Exclusion Principle not applied beyond a Neutron Star's mass?" since there may not be a full quantum gravity theory yet, however, I'm thinking, what if Pauli Exclusion Principle is not really a principle, but an indication...

I discovered the existence of Pauli's exclusion principle from this section of this video here: http://www.youtube.com/watch?v=4f9wcSLs8ZQ&t=35m30s If you watch it for a bit, he explains that it applies to the whole universe. Is this true? On Wikipedia it says otherwise...

Watching Brian Cox "BBC - Professor.Brian.Cox.A.Night.With.The.Stars - 2011" After 34 min he starts to talk about Pauli exclusion principle No electron can be in the same energy state he says. This is not just true for an atom a molecule or the diamond he is showing. No this goes for...

Homework Statement It's not a homework question. It's a piece of my textbook I don't understand. Here's what it says In a two electron atom, taking the orbital states of two electrons to be the same, then the antisymmetric wavefunction tends to zero, as well as the quantum numbers n, l and...

I don't want to name him explicitly, in fear of blemishing his name in case he is not a fraud. Just google (including the ""-symbols) and the relevant wikipedia page should be the first hit. Apparently the scientist first went to a group established in 1975, and afterwards he went to work...

Hello guys, here's something that's been bothering me for a while now: We know the Pauli exclusion principle states that 2 Fermions cannot be in an identical state. So then we have systems like solids or free electron gases, and we calculate and form Fermi-Surfaces, based on the fact that...

Hey guys, I was wondering how to get the expression for pauli matrices. I know that for one electron: S_i = \frac{\hbar}{2} \sigma_i But I also know that you can get to the above expression by explicitly calculating the matrix elements of the Sz, Sx and Sy operators (in the basis generated...

Is Pauli exclusion principle due to magnetic interactions between spins of electrons?

The principle states that no two identical fermions in a system can be in the same quantum state, but what I don't fully understand is how you define a "system". For example when you apply statistical thermodynamics to a gas of non-interacting fermions you say that a maximum of one can occupy...

Hi, We know that the Pauli matrices along with the identity form a basis of 2x2 matrices. Any 2x2 matrix can be expressed as a linear combination of these four matrices. I know of one proof where I take a_{0}\sigma_{0}+a_{1}\sigma_{1}+a_{2}\sigma_{2}+a_{3}\sigma_{3}=0 Here, \sigma_{0} is...

The Pauli Exclusion Principle is the reason more than two electrons cannot occupy the same orbital. This is easy for me to grasp. Why, then, does the Pauli Exclusion Principle make an orbital MORE stable with two electrons as opposed to one? (This is in the interest of knowledge. I'm not...

Kindly ignore if some +- signs are placed wrongly in the equations. Thank you. Rotation in three dimensions can be represented using pauli matrices \sigma^{i}, by writing coordinates as X= x_{i}\sigma^{i}, and applying the transform X'= AXA^{-1}. Here A= I + n_{i}\sigma^{i}d\theta/2. The pauli...

Homework Statement Consider a 1/2-spin particle. Its time evolution is ruled by operator U(t)=e^{-i\Omega t} with \Omega=A({\vec{\sigma}}\cdot {\vec{L}})^{2}. A is a constant. If the state at t=0 is described by quantum number of {\vec{L}}^2, L_{z} and S_{z}, l=0, m=0 and s_{z}={1/2}...

Hello, I have a question concerning the use of wavepackets to justify the semiclassical approach in solid state physics. In Ashcroft/Mermin, the authors briefly mention that we can construct wave packets and then use them to describe the motion of the center which can be interpreted as what...

Hi, Given the two relations below, is it true and if yes, can anyone help me show that the solution to this must be the Pauli matrices? The alphas are matrices here. \alpha_{i}\alpha_{j}+\alpha_{j}\alpha_{i} = 2\delta_{ij}*1. 1 is the identity matrix \alpha_{i}^{2} = 1 Thank you

Homework Statement What is the result of operating on the state |+> with the operator Sx? here, |+> denotes the eigenstate of Sz with eigenvalue 1/2. I am working in units where h-bar is 1 (for simplicity, and because I don't know how to type it) Homework Equations S_i = \frac{1}{2} σ_i The...

Hey guys There are those vectors made of Pauli matrices like \bar{\sigma}^\mu and {\sigma}^\mu. So if I have the product \bar{\sigma}^\mu {\sigma}^\nu I wonder if it is commutative? And if not, what is the commutator? Cheers, earth2

This morning I've been thinking about a simple problem whose I can't find out a satisfying solution. We all know that two "close" fermions can't exist in a up-up or down-down spin configuration because of vanishing state function as expressed by the exclusion principle. But what does...

definition of "indistinct" in pauli exclusion principle I'm a little confused about what constitutes a distinct particle. For example, a muon is not an electron as they've got different masses. So the wavefunction for the electron/muon system does not have to be antisymmetric (although it can...

As I understand it, the Pauli exclusion principle states that no two like fermions can be in identical quantum states. I also understand that the quantum states are thus: n, which is the electron shell, l, which is the subshell, m_{l}, which is orbital, and m_{s}, which is spin. However, it...

Suppose there are only two states, and that only two electrons could fit in them (spin states for example), but wouldn't these two states form a basis and so generate an infinite number of states that are linear combinations of these two, so three electrons could be in three different states...

If you look up the second quantization spin operator, you'll notice that there are two indices on the pauli vector for two possible spins. The operator sums over these two indices. Since the pauli vector is an unchanging quantity what do these indices physically correspond to?

[b]1. Homework Statement [/ from the ets general physics practice test (ill take it in april) the state of spin 1/2 particles using the eigenstates up and down Sz up= 1/2 hbar Sz down= -1/2 hbar Homework Equations given sigmax (pauli spin matrix) which of the following list...

The Pauli Spin matrices: \sigma_1=\left[ \begin{array}{ c c } 0 & 1 \\ 1 & 0 \end{array} \right],\sigma_2=\left[ \begin{array}{ c c } 0 & -i \\ i & 0 \end{array} \right],\sigma_3=\left[ \begin{array}{ c c } 1 & 0 \\ 0 & -1 \end{array} \right] are used...

Does anybody know a good thread, homepage or book that takes up different interpretations of Pauli and Dirac matrices with the connection to for example quaternions or bivectors? Maybe someone could comment on this?

Hello, I attached a copy of the problem and my attempted solution. The three Pauli spin matrices are given above the problem. I'm having trouble getting the right side to equal the left side, so I'm assuming I'm doing something wrong. When I got towards the end it just wasn't looking right...

hi, can we say that the Pauli exclusion principle between 2 identical fermions implies logically entanglement because of the antisymmetric wavefunction, that can not be factorized as a tensor product: http://en.wikipedia.org/wiki/Slater_determinant "However, it is not satisfactory for...

hi, anyone can enlighten me why the pauli x matrix in the z basis is given as 0 1 1 0 while it in the x basis, it is given as 1 0 0 -1 is there a formula or something to calculate this? and how does one know that a matrix is in the z basis or the x basis? thanks a lot!

If we consider the spin-1/2 pauli matrices it makes sense that [S_x,S^2] = [S_y,S^2] = [S_z,S^2] = 0 since S^2 = I... and this is supposed to be true in general, right? Well, if I attempt to commute the spin-1 pauli matrices given on http://en.wikipedia.org/wiki/Pauli_matrices, with...

"Pauli matrices with two spacetime indices" Hi all. This is my first post so forgive me if my latex doesn't show up correctly. I am familiar with defining a zeroth Pauli matrix as the 2x2 identity matrix to construct a four-vector of 2x2 matrices, $\sigma^\mu$. I'm trying to read a paper...

I'm completely lost and need some advice on how to continue. I need to prove the 1st line on the link http://upload.wikimedia.org/math/0/f/8/0f873eaca989ffa1af9a323c6e62f3ed.png

hi, i believe there is a clear cut relationship between the pauli exclusion principle and the thermodynamical/chemical stability in chemistry. the pauli principle rises the energy level, and stability occurs for the lowest energy states. does that mean that a consequence of the pauli...

does Pauli exclusion principle applied outside the atom?let say 1 electron on Earth and the other on the moon.

I'm reading an article (http://prb.aps.org/abstract/PRB/v82/i4/e045122) but I have some problems understanding certain definitions. The authors have introduced a basis of certain bands (four) and then continue to give the transformation matrices of the symmetry operators. One (rotation) of them...

Homework Statement In the absence of the Pauli principle, the Coulomb force would not be saturated, and the energy of a system containing N atoms would vary as N^(5/3). Show that a system of 2N atoms would have an energy lower than that of two N - atom systems. Homework Equations E...

Homework Statement By using the general density matrix rho find the average of the three Pauli matrices. You can then tell how many independent experiments you must make in order to determine rho. Homework Equations The Attempt at a Solution I know the Pauli matrices and their...