Massive N^2 speedup by implementing translational symmetries in Fourier Space#10
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mesonepigreco wants to merge 1 commit intomainfrom
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Massive N^2 speedup by implementing translational symmetries in Fourier Space#10mesonepigreco wants to merge 1 commit intomainfrom
mesonepigreco wants to merge 1 commit intomainfrom
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The replica symmetry problem has been fixed for the \Gamma only flag #13 So this is still a TODO, as an additional N scaling can be gained for Gamma perturbation and a N^2 for out-of-Gamma perturbations |
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This branch should implement the calculation of the perturbation directly in Fourier Space.
This is obtained by exploiting the relation
This means that this relation can be written as block diagonal, obtaining a N-scaling speedup in case of large supercell.
Not only, this automatically impose the translational symmetry, getting an additional N scaling advantage over the fully replica symmetries algorithm currently implemented as the fast_lanczos algorithm. This implementation should therefore produce a N^2 scaling, bringing the application of Lanczos + v4 on the same computational cost as the standard SSCHA.