140 reputation
5
bio website
location Germany
age 42
visits member for 1 year, 7 months
seen Jan 25 at 21:26

Research interests: surface science (experiment), vibrational spectroscopy, Monte Carlo simulations, statistical physics.


Dec
18
comment Noise spectrum of two systems and interacting Hamiltonian
The volumes in the Landau-Lifshits series are devoting a lot of space to this type of arguments, which you could read with much profit. It is called the linear response theory, and it is extensively discussed in vols. "Statistical Mechanics", "Electrodynamics of Continua" but is popping up now and again in the entire series. They call your noise spectrum a "generalized susceptivity" and prove strong results like the Kramers-Krönig and the Fluctuation-Dissipation theorems.
Dec
16
comment Electron hopping among molecules - Marcus equation
In case your model is of the kinetic Monte Carlo type (plausible by your description) the only quantities you will need for the time evolution are the hopping rates R. Then the probability of a simulated jump $P(n \rightarrow l)$ is as writen above. You will have to take care that the forward and backward \it{rates} $R_{n \rightarrow l}$ and $R_{l \rightarrow n}$ (prob/s, and not the jump probabilities as such) are defined such that they obey the principle of detailed balance.
Dec
16
comment Explanation on Atomic Orbitals and Molecular Orbitals
In the theory of molecular orbitals (MO) you consider the movement of a single electron in the Coulomb field produced by the "naked" atomic nuclei of your molecule ("moiety"). In this sense the MO theory is a one-electron model and as such, it has nothing to do with the Pauli Principle. In the first step (i) you set up the possible MOs for your molecular moiety. You end up with a set of MOs ordered after their energy. In the second step (ii) you fill up these MOs with 2 elos each, in order of increasing energy, until you run out of elos. It is only in (ii) that the Pauli Principle is applied.
Sep
17
comment Are the field lines the same as the trajectories of a particle with initial velocity zero
I am so sorry. I will retract my post, the single one I can do.
Sep
16
comment Are the field lines the same as the trajectories of a particle with initial velocity zero
... that I found it.
Sep
16
comment Are the field lines the same as the trajectories of a particle with initial velocity zero
Dear Emilio, would you accept that my answer (which contains exactly what you said) remains posted here? I was so happy that
Sep
16
comment Crystal magnetic response only skin deep?
That is correct, you gave the derivation of the Meissner effect. But my point was that your $j$ contains the also the cross product terms, and what their effect could be has still to be worked out. After all each current density will contain a London-type term, yet superconductivity is seldom. I am afraid we deal in this case with a similar situation (i.e. no skin effect).
Sep
16
revised Carnot Engine for Finite Reservoirs
improved formatting
Sep
16
comment What are distinguishable and indistinguishable particles in statistical mechanics?
Besides this problem, there are quite a few features of classical Statistical Mechanics which are reminiscent of QM, although they were developed one or two decades before QM. It would be very interesting to clarify once and for all how much actual QM is contained in these "classical" assumptions of Statistical Mechanics. Examples of these problematic classical features include all equations where $\hbar$ actually appears (e.g. the Sackur-Tetrode Eq., the integration measure in phase space ${\frac{1}{N!}\(\frac{dp\ dq}{2 \pi \hbar}\)}^N$) as well as the third principle of Thermodynamics.
Sep
16
comment Crystal magnetic response only skin deep?
Are you sure that $\bf{A}$ is penetrating here only skin-depth? In the London Equation this was true, but there the first term in the current density was negligible. Possibly is the analogy flawed.
Sep
16
suggested suggested edit on Carnot Engine for Finite Reservoirs
Sep
15
revised Does a material exist that reduces a magnetic field without being affected by the magnetic field itself?
picture added
Sep
15
revised Does a material exist that reduces a magnetic field without being affected by the magnetic field itself?
improved readability
Sep
15
revised Does a material exist that reduces a magnetic field without being affected by the magnetic field itself?
improved readability
Sep
15
comment In what way do Cooper pairs of electrons bond and stay bonded in superconductors?
Kittel's Quantum Theory of Solids is also a good starter, an exposition of the full quantized theory but at a very accessible level.
Sep
14
revised Does a material exist that reduces a magnetic field without being affected by the magnetic field itself?
corrected spelling
Sep
14
answered Does a material exist that reduces a magnetic field without being affected by the magnetic field itself?
Sep
13
comment Linewidth pressure broadening due to organic molecules
Is the chemical nature of the partner gas B influencing line broadening for gas A? Is B not equivalent to a noble gas at the same partial pressure? My understanding is that broadening of lines of A originates in the partial component B being a collision "reservoir" which perturbs absorption by gas A.
Sep
13
revised Driving a solution of optical isomer molecules with the resonant frequency
added 9 characters in body
Sep
13
comment Driving a solution of optical isomer molecules with the resonant frequency
Sorry folks for communicating the wrong result: the system simply oscillates between the two states, there is no 50%-50% separation. This came because I forgot an $\sqrt{-1}$ in the time evolution. To model the situation you need to address the full Master Equation with decoherence included (Lindblad Eq.).