GISAXS form periodic boxes


I have a molecular model of a block copolymer film, which gives some non-uniform refractive index distribution in the box with periodic boundary conditions in x and y directions. I used Particle Composition, assemblied from smaller boxes, to simulate this big piece of the film and I met several problems. One is the limited number of boxes in the particle composition. My 3D mesh has dimensions 50x50x30, for example, but with this number of boxes (75000) BornAgain 1.4 don't have enough memory, so i reduced the system size to about 10000 boxes (with the loss of resolution, of course). Could you reccomend something in this case, please?The second question is which interference function is more suitable for the simulation of multiple periodic boxes in x-y plane? It seems for me that the most suitable is 2D paracrystal. On the other hand, the scattering should be averaged over different orientations of the system around z-axis. I found implementation of this rotation in 2D lattice, but not in 2D paracrystal. Could you explain (or give a link) please, how to do this rotation correctly with 2D paracrystal?

Is is difficult to implement such kind of structures, like known distribution of refractive indexes on the periodic cubic mesh into BornAgain? I understand that this is maybe much longer story, but many molecular simulations can produce exactly this kind of input data.

Best regards,Anatoly.

herck's picture

Hi Anatoly, I tried on my linux system (which has 32GB) the 75K particles you mentioned and got a usage of 4GB. So this could still be handled here. Are you using Windows? Because we will release 64bit Windows installers in the near future, which will remove some memory restrictions. Regardless of memory constraints, the right way of simulating such a structure would be to define a certain domain structure on the sample (given by the two-point correlation function of scattering density/refractive index). This is currently not supported in BornAgain but is included in our long term planning. If you want, we could support you directly in the simulation of the samples you have in mind. This would also allow us to get a better picture of what is needed. I will send you an email so you can contact us directly. Best regards, Walter