CalcTau Subroutine

    SUBROUTINE CalcTau
        !Detemines tau for a given lattice type

        if (dimen == 3) then ! 3D
            ! Hij_min**-1
            call assign_value_to_tau((k_lattice_constant**2 * OMEGA) / (4.0_dp * PI), &
                'Initialization in System_neci.')
            if (tTruncInitiator) call assign_value_to_tau(TAU * InitiatorWalkNo, 'Initialization in System_neci.')
            if (tHPHF) call assign_value_to_tau(TAU / sqrt(2.0_dp), 'Initialization in System_neci.')
            call assign_value_to_tau(0.9_dp * TAU * 4.0_dp / (NEL * (NEL - 1)) / (NBASIS - NEL), &
                'Initialization in System_neci.')
            if (TAU > k_lattice_constant**(-2) / OrbEcutoff) then
                ! using Hii
                call assign_value_to_tau(1.0_dp / (k_lattice_constant**(2) * OrbEcutoff), &
                    'Initialization in System_neci.')
                write(stdout, *) '***************** Tau set by using Hii *******************************'
                !write(stdout,*) 1.0_dp/((2.0_dp*PI/Omega**third)**2*orbEcutoff)
            else
                write(stdout, *) 'Tau set by using Hji'
            end if

        else if (dimen == 2) then !2D
            ! Hij_min**-1
            call assign_value_to_tau((k_lattice_constant * OMEGA) / (2.0_dp * PI), &
                    'Initialization in System_neci.')
            if (tTruncInitiator) call assign_value_to_tau(TAU * InitiatorWalkNo, &
                    'Initialization in System_neci.')
            if (tHPHF) call assign_value_to_tau(TAU / sqrt(2.0_dp), 'Initialization in System_neci.')
            call assign_value_to_tau(0.9_dp * TAU * 4.0_dp / (NEL * (NEL - 1)) / (NBASIS - NEL), &
                    'Initialization in System_neci.')
            if (TAU > k_lattice_constant**(-2) / OrbEcutoff) then
            !!!!!!!! NOT WORKING YET!!!!!!!
                !using Hii
                call assign_value_to_tau(1.0_dp / (k_lattice_constant**(2) * OrbEcutoff), &
                    'Initialization in System_neci.')
                write(stdout, *) '***************** Tau set by using Hii *******************************'
            else
                write(stdout, *) 'Tau set by using Hji'
            end if

        else if (dimen == 1) then !1D
            call assign_value_to_tau(OMEGA / (-2.0_dp * log(1.0_dp / (2.0_dp * sqrt(orbEcutoff)))), &
                    'Initialization in System_neci.')
            if (tTruncInitiator) call assign_value_to_tau(TAU * InitiatorWalkNo, &
                    'Initialization in System_neci.')
            if (tHPHF) call assign_value_to_tau(TAU / sqrt(2.0_dp), &
                    'Initialization in System_neci.')
            call assign_value_to_tau(0.9_dp * TAU * 4.0_dp / (NEL * (NEL - 1)) / (NBASIS - NEL), &
                    'Initialization in System_neci.')
            if (TAU > 0.9_dp * 1.0_dp / (0.5_dp * (k_lattice_constant)**2 * NEL * OrbEcutoff)) then
                ! using Hii
                call assign_value_to_tau(0.9_dp * 1.0_dp / (0.5_dp * (k_lattice_constant)**2 * NEL * OrbEcutoff), &
                    'Initialization in System_neci.')
                write(stdout, *) '***************** Tau set by using Hii *******************************'
            else
                write(stdout, *) 'Tau set by using Hji'
            end if

        end if !dimension
        write(stdout, *) 'Tau set to: ', TAU
        return
    END SUBROUTINE CalcTau