KERNEL TRUNCATION/LCOARSEN

KERNEL_TRUNCATION/LCOARSEN = .True. | .False.
Default: KERNEL_TRUNCATION/LCOARSEN = .True. 

Description: KERNEL_TRUNCATION/LCOARSEN speeds up computation of the local potential in the kernel truncation method by coarsening the charge density before padding it

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Kernel truncation methods pad the computational cell with vacuum. This padded cell is expensive to compute due to FFTs being performed on a larger grid. The KERNEL_TRUNCATION/LCOARSEN method selectively replaces the long range potential with the truncated potential instead of computing the entire potential on a padded grid. This selective replacement of the potential bypasses the need for padding, speeding up the computation of the kernel truncation methods.