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LSCALU = [logical]
Default: LSCALU = .FALSE.
Description: LSCALU switches on the parallel LU decomposition (using scaLAPACK) in the orthonormalization of the wave functions.
For LSCALU=.TRUE. the LU decomposition in the orthormalization of the wave functions is done in parallel, using scaLAPACK routines. Provided, of course, LSCALAPACK=.TRUE. and VASP was compiled with scaLAPACK support (precompiler flag: -DscaLAPACK).
In many cases, the scaLAPACK LU decomposition based is slower than the serial LU decomposition (compare the timing ORTHCH in the respective OUTCAR files). Hence the default is LSCALU=.FALSE. (subspace rotations, however, are still done using scaLAPACK).