Recent content by jackychenp

Dear All, I have a paramagnetic material, its magnetic moment will saturate at magnetic field of 30 T (all spins align in the field direction). So shall I treat the high field phase as a ferromagnetic phase when I do electronic calculations?

Thanks.

For a ferromagnetic material in the hysteresis loop, when increasing field from H=Hc, its magnetization (M) will saturate. But if we decrease field instead, will M decreases clockwise according to the loop? How can we make the ferromagnetic material back into the initial state (H=0, M=0)...

Hi Mute, In Dirac's book, he demonstrates that if A=B, one can't infer A/x=B/x, but only A/x=B/x+cδ(x). I cannot get the latter result. And if we integrate the latter equation, it doesn't look correct.

From dirac, if A=B, then \frac{A}{x}=\frac{B}{x}+c\delta(x) (1) How this formula is derived? Since \frac{dlnx}{dx} = \frac{1}{x}-i\pi\delta(x) We can get \frac{A}{x} = A\frac{dlnx}{dx}+Ai\pi\delta(x) \frac{B}{x} = B\frac{dlnx}{dx}+Bi\pi\delta(x) So if A=B, \frac{A}{x}=\frac{B}{x}...

Thanks a lot!

Hi All, \int_{0}^{2\pi}d\varphi \int_{0}^{\pi}\sqrt{\frac{1}{1-sin^2\theta cos^2\varphi }}d\theta I tried very hard to evaluate this integral but failed. Please help me if you know how to solve it.

Does that mean double slits diffraction will not work if sources on two slits are different, say electrons in one slit, alpha particles in the other? This is weird since both can be see as waves just with different wavelength, and the interference should occur.

Hi, I am new to QM and really confused with some concepts. Assume two alpha particles come out from two different sources and reach the same detector, so the probability to detect some particles should be |f+g|^2 (f, g are the amplitude of 1st and 2nd alpha particle, respectively). If they are...

Vanhees, thanks for your fabulous comments. clem, I forgot a factor 1/2. Thanks for pointing it out.

From EM, the energy of electromagnetic wave in unit volume is \varepsilon_0 E^2. Does that mean the number of photon is \varepsilon_0 E^2/\hbar\omega ( \omega is frequency of wave)? In 1-D, E=E_0cos(\omega t+kx), then the number of photon in average is \frac{1}{(2\pi/\omega)}\int_{0}^{2\pi...

Hi cgk, Do you mean integrate in the whole Brillioun Zone to get Wannier orbitals? In that case, one wave function psi(k) is just part of orbitals.

Hi All, For a hydrogen atom in the field B, torque on the electron is \tau =\mu Bsin\theta =\omega_pJsin\theta => \omega_p=gqB/(2m) If we only consider orbital motion (ignore spin), then g=1. So \omega_p=qB/(2m). (It follows the steps from Feynman's lectures VII section 34-3) For a single...

Hi All, There is a simple question in my mind. A band with energy Ek has dispersion in k space. Then what it looks like in the real space?

Neumaier, thanks for your patience. I appreciate your help!