Recent content by boyu

I am trying to prove the variational principle on 1st excited state, but have some questions here. The theory states like this: If <\psi|\psi_{gs}>=0, then <H>\geq E_{fe}, where 'gs' stands for 'grand state' and 'fe' for 'first excited state'. Proof: Let ground state denoted by 1, and...

Thanks for your reply, but I guess we still need to consider the angle between \mu and B, right? And this angle is also given by the angle between L and S, since \mu is parallel to S and B is parallel to L. Thus, cos\theta=\frac{j(j+1)-l(l+1)-s(s+1)}{2\sqrt{l(l+1)s(s+1)}}, since...

There are two cases introduced in the lecture notes, depending on strength of spin-orbital coupling in individual electrons, since V_{SL} \propto Z^{4}. 1) jj coupling, which is valid for large-Z atoms, where spin-orbital coupling > electrostatic replusion between electrons 2) L-S coupling or...

Consider the D1 and D2 transitions (3p --> 3s) of the sodium atom (Z = 11). How to calculate the magnetic field experienced by the valence electron arising from its orbital motion, given that the wavelength difference between the D lines? The formula that I have from lecture notes for...

Many thanks! ^_^

How to get 15 from counting the multiplicities from correct states? The spin multiplicities are 1, 1, 3, 3 & 3.

The ground state electron configuration of Carbon atom is 1s^{2}2s^{2}2p^{2} For the electrons, 1s^{2}2s^{2}, L=0, S=0 So only consider electrons of 2p^{2}, and s_{1}=s_{2}=1/2 ---> S=0,1 l_{1}=l_{2}=1 ---> L=0,1,2 For S=0, L=0; J=0, so we have ^{1}S_{0} For S=0, L=1; J=1, so...

Homework Statement A Hydrogen atom is initially in its ground state and then subject to a pulsed electric field E(t)=E_{0}\delta(t) along the z direction. We neglect all fine-structure and hyperfine-structure corrections. Homework Equations 1. It is important to use selection rules to avoid...

Actually the average grade for major modules (physics) is around B- or B. Part of the reasons for this low gpa is that I took too many irrelevant modules which I'm not good at but strongly interested in, like psychology, economics, foreign languages, etc... It is until the last yr when I...

urs may be the longest reply that I've received.. thx, really, this is quite helpful, especially the interview part which has always troubled me a lot. Btw, what r u doing now?

well it is this low like 2.5 out of 5.

Hi, this is a undergraduate student who is graduating in this Dec. Honestly, my GPA is quite low. Do u think that, does such a person like me still have the opportunity to pursue a master's degree in physics, or even a P.hD.?

Yeah, you're right. I went through these elements and found that they indeed equal to zero. As a result, the perturbed wave function can only be a linear combination of state \psi_{21-1} and \psi_{211}, namely the state \psi_{200} and \psi_{210} unaffected by the perturbation. Moreover, sum of...

Your equation is for calculating B from current, but in this question the B field is already there before the electrons went into, and this B field also accounts for the centripetal force which pulls the electrons into circular motion, provided the fact that the electrons have velocities after...

Are you doing error analysis? I guess you may have to go through the detailed procedure of ur experiment to look for any possible reason that may account for the error, i.e., the surrounding, the ways of measuring and recording, etc.