On May 16, 2011, at 1:44 AM, Rachele Nerattini wrote:
Dear all,
I have a few questions too about simulations with spinmc application.
I'll make a specific example so I hope it'll be more clear... I have to run a MC classic simulation of the XY model defined on a square lattice with periodic boundary conditions. I wrote the following input file:
LATTICE_LIBRARY="lattices.xml" LATTICE="square lattice" T=0.892936869 J=1 THERMALIZATION=50000 SWEEPS=1000000 UPDATE="cluster" MODEL="XY" BOUNDARY type="periodic" S=1 {L=64;} {L=128;}
so that the simulation is performed for two different lattice sizes. I did it following the instruction on the tutorials and it seemed to work. The questions are:
- Which are the initial conditions at the beginning of the simulation? Are the spins spread randomly on the lattice?
No, they are all aligned - but it is easy to change that in the code.
- Is it possible to save the configurations which are used for the calculations of the observables? I suppose the program generates a certain number of configurations then on one of them it takes the values of the observables and then it makes other pure dynamic MC steps and then it take again the measure of the observable on another configuration and so on...Is it correct? Can I save those configurations used for the accumulation of the observables?
Yes, it is possible, however this is not efficient. Using cluster updates generating a new configuration takes about as much time as reading it from disk.
- I also would like to know if is it already possible to compute the density of vortix in this model...But I suppose this observable has to be added editing some of the spin mc files....
Yes, you need to add that to the code.
- If now I want to run the same simulation but for a three dimensional simple cubic lattice is it correct to write
LATTICE="simple cubic lattice" instead of LATTICE="square lattice" as above?
Yes, that should work
Matthias