Hi everyone,
I'm reading DMRG tutorials in http://alps.comp-phys.org/mediawiki/index.php/ALPS_2_Tutorials:DMRG-01_DMRG. and http://alps.comp-phys.org/mediawiki/index.php/ALPS_2_Tutorials:DMRG-02_Gaps It suggested me to extrapolate energies and energy gaps to D(maxstates) -> infinity.
The question is about nonlinear extrapolation. In the case spin 1/2 gap versus 1/L, there is a linear relation and I can easily polyfit it linearly and get the gap in L->Inf limit. But in the case of quantities such as gaps versus D(maxstates), there is no simple linear relation. For example: Each time I enlarge D by 50, energy gaps change by the following values: [ -2.49851713e-08, -1.45270462e-11, -2.84217094e-14, -5.50670620e-14] which slows down changing by smaller and smaller values. I have done some exponential curve fittings in matlab but it become confusing when you have many models to fit it. How can I extrapolate such a nonlinear curve to D->Inf limit? Is there any standard way to do this?
LiuBiao ll070616@126.com