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    Is the energy density normalized differently in the quantum case?

    Hi all, This is all in the context of interaction between (two-level) atoms and an electromagnetic field, basically the Wigner-Weisskopf model. In particular, I tried to derive the value of the atom-field interaction constant and show that it satisfied...
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    Simplifying many body operator expressions

    Hello all, Is there any really good software, package or otherwise, that is helpful for simplifying long operator expressions, particularly with (anti-commuting) electron operators? For example, I'd like to be able to transform Hamiltonians, project onto subspaces with specific occupation...
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    P orbital notation

    Hi, Reading http://rmp.aps.org/abstract/RMP/v70/i4/p1039_1 I've run into a notational question of atomic p orbitals. The authors use symbols like p_\sigma and p_\pi. From their fig. 3 (attached), they do look like p_x and p_z orbitals, respectively, rather than anything close to σ or π bonds...
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    Lagrangians giving the same equations of motion

    Hi, I'm trying to clear up a confusing point in the book by José and Saletan, concerning equivalent Lagrangians (in the sense that they give you the same dynamics). It is clear that if L_1 - L_2 = \frac{d\phi ( q,t )}{dt}, then L_1 and L_2 will have the same equations of motion. However...
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    Calculation of a particular functional (path) integral

    Hello! On p.424 in the second edition of Altland & Simons, they compute an average as part of a renormalization group analysis of a model for dissipative quantum tunneling. I'd like to use their result in another situation, but I would be much happier if I understood how they derived it. I have...
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    How to dry a SF6 tank?

    Hello, Now that I have an actual problem (in summer work) I thought I'd take the step from occasional forum lurking to actually post. A customer have recently had some problems with moisture in a tank of insulating SF6 gas, protecting some 300kV electronics. Allow me to outline the...
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