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seen Dec 9 at 16:14

Piece of cheese


Nov
18
asked Ising Monte-Carlo and Three point functions
Sep
24
awarded  Autobiographer
Sep
8
comment How do you measure numerically the central charge of a system?
Is you answer about measuring an electric charge? I'm interested in 'measuring' numerically the central charge which is a number characterizing a conformal field theory. Thank you anyway, I was confused when I started to read your answer =)
Sep
5
comment How do you measure numerically the central charge of a system?
@Holographer: I had found these, just haven't been able to implement them in my current system, so I'm seeking alternative methods.
Sep
5
comment How do you measure numerically the central charge of a system?
Yes, in 2d. If that matters I'm looking at two dimensional spin systems.
Aug
25
comment Non translation invariant correlator in CFT
@Trimok: Indeed taking two derivates (one with respect to $w$ and one with respect to $z$) gives the translation invariant power law. (The additive factor I was talking about gives zero when derived twice). Thus it works for the first correlation function but the second one is still obscure. Many thanks for the suggestion ;)
Aug
23
comment Non translation invariant correlator in CFT
@Trimok: the commutator you are referring to is $\langle\tilde{\phi(z)}\tilde{\phi(w)}\rangle= ln(z-w)$ which is translation invariant but different from the one given on this page (addictive factor $- ln(z)$)
Aug
23
reviewed Approve Non translation invariant correlator in CFT
Aug
23
asked Non translation invariant correlator in CFT
Aug
20
asked How do you measure numerically the central charge of a system?
Jul
8
comment Numerical Ising Model - Wolff algorithm and correlations
depending on the energy shift from breaking links to the boundary and with fixed boundaries a lot of rejection occurs), but with free boundaries, a low T starting point is roughly 4 times faster.
Jul
8
comment Numerical Ising Model - Wolff algorithm and correlations
Interesting, I have a different way of reaching equilibrium I would first monitor the value of the mean energy per spin (for each configuration) and read from there how many steps I needs for each systems size (I usually stick to 3,4 sizes also). I did check if starting from a totally ordered configuration is quicker than a totally disordered, and well amusingly it depends on the boundary conditions: with fixed boundaries, disordered is very very advantageous (the reason it that the Wolff algorithm needs to be modified with fixed boundaries with an accepting factor 'à la Metropolis'
Jul
7
comment Numerical Ising Model - Wolff algorithm and correlations
Thank you very much for the input, I will look deeper at your code. Can I ask you how many systems did you simulate (ie. are you averaging on) ? I managed to derive a good coefficient in my case too (very close to 0.249 ) but my data was noisier, probably the sum used to fit (linearly in log-log scale) cancelled most of the noise. Also how many Wolff evolution steps do you perform to thermalize starting from ordered T = 0 configurations? Many thanks again ;)
Jul
7
accepted Numerical Ising Model - Wolff algorithm and correlations
Jul
4
accepted What is a 'height field'?
Jul
4
comment What's the critical temperature of the XY model on a triangular lattice
Yes, indeed they do locate the critical temperature using the 4th Binder cumulant, though my simulations are giving me different results on the x and y axis, I definitely need to look deeper into that. Many thanks ;)
Jul
4
accepted What's the critical temperature of the XY model on a triangular lattice
Jul
3
asked What's the critical temperature of the XY model on a triangular lattice
Jul
2
comment Critical temperature difference between Ising and XY model
Right, makes sense!
Jul
2
awarded  Curious