FindExcitBitDetSym Subroutine

public pure subroutine FindExcitBitDetSym(iLut, iLutSym)

Arguments

Type IntentOptional Attributes Name
integer(kind=n_int), intent(in) :: iLut(0:NIfTot)
integer(kind=n_int), intent(out) :: iLutSym(0:NIfTot)

Source Code

    PURE SUBROUTINE FindExcitBitDetSym(iLut, iLutSym)
        IMPLICIT NONE
        INTEGER(KIND=n_int), intent(in) :: iLut(0:NIfTot)
        INTEGER(KIND=n_int), intent(out) :: iLutSym(0:NIfTot)
        INTEGER(KIND=n_int) :: iLutAlpha(0:NIfTot), iLutBeta(0:NIfTot)
        INTEGER :: i

        iLutSym(:) = 0
        iLutAlpha(:) = 0
        iLutBeta(:) = 0

        do i = 0, NIfD

            iLutAlpha(i) = IAND(iLut(i), MaskAlpha)    !Seperate the alpha and beta bit strings
            iLutBeta(i) = IAND(iLut(i), MaskBeta)

            iLutAlpha(i) = ISHFT(iLutAlpha(i), -1)  !Shift all alpha bits to the left by one.
            iLutBeta(i) = ISHFT(iLutBeta(i), 1)   !Shift all beta bits to the right by one.

            iLutSym(i) = IOR(iLutAlpha(i), iLutBeta(i))    !Combine the bit strings to give the final bit representation.

        end do

    END SUBROUTINE FindExcitBitDetSym