readTimeEvolvedState Subroutine

    subroutine readTimeEvolvedState()
        use PopsfileMod, only: FindPopsfileVersion, ReadPopsHeadv4, InitFCIMC_pops, &
                               open_pops_head
        use semi_stoch_gen, only: init_semi_stochastic
        use semi_stoch_procs, only: end_semistoch
        use real_time_procs, only: reset_core_space
        use CalcData, only: ss_space_in
        use FciMCData, only: TotImagTime
        implicit none

        integer :: iunit, popsversion, iPopLenof_Sign, iPopNel, iPopIter, &
                   PopNIfD, PopNIfSgn, PopNIfFlag, PopNIfTot, &
                   PopBlockingIter, Popinum_runs, PopRandomHash(2056), &
                   read_nnodes, PopBalanceBlocks
        logical :: formpops, binpops, tPop64Bit, tPopHPHF, tPopLz
        integer(int64) :: iPopAllTotWalkers, read_walkers_on_nodes(0:nProcessors - 1)
        real(dp) :: PopDiagSft(inum_runs), PopModDiagSft(inum_runs), read_tau, PopSumNoatHF(lenof_sign), &
                    read_psingles, read_pparallel
        HElement_t(dp) :: PopAllSumENum(inum_runs)
        integer :: ierr
        logical :: tStartedFromCoreGround
        character(255) :: rtPOPSFILE_name
        character(*), parameter :: this_routine = "readTimeEvolvedState"
        real(dp) :: unused_triples

        if (tSemiStochastic) then
            ! if semi-stochastic mode is enabled, it has to be disabled for read-in again
            ! as load balancing has to be performed
            call end_semistoch()
            call reset_core_space()
        end if

        binpops = .false.

        rtPOPSFILE_name = 'TIME_EVOLVED_POP'

        ! get the file containing the time evolved state
        call open_pops_head(iunit, formpops, binpops, rtPOPSFILE_name)

        popsversion = FindPopsfileVersion(iunit)
        if (popsversion /= 4) call stop_all(this_routine, "wrong popsfile version of TIME_EVOLVED_POP")

        call ReadPopsHeadv4(iunit, tPop64Bit, tPopHPHF, tPopLz, iPopLenof_Sign, iPopNel, &
                            iPopAllTotWalkers, PopDiagSft, PopModDiagSft, PopSumNoatHF, PopAllSumENum, iPopIter, &
                            PopNIfD, PopNIfSgn, Popinum_runs, PopNIfFlag, PopNIfTot, &
                            read_tau, PopBlockingIter, PopRandomHash, read_psingles, &
                            read_pparallel, unused_triples, read_nnodes, read_walkers_on_nodes, PopBalanceBlocks)

        ! at this point, we do not want to perturb the state and have no use for the
        ! pops_pert variable anymore -> deallocate it

        ! read in the hacked shift_damping
        if (.not. allocated(shift_damping)) allocate(shift_damping(inum_runs), stat=ierr)
        shift_damping = PopSumNoatHF(1:inum_runs)

        call clear_pops_pert(pops_pert)

        ! read in the time evolved state and use it as initial state
        call InitFCIMC_pops(iPopAllTotWalkers, PopNIfSgn, iPopNel, read_nnodes, &
                            read_walkers_on_nodes, pops_pert, &
                            PopBalanceBLocks, PopDiagSft, rtPOPSFILE_name)

        call set_initial_times(read_tau, TotImagTime, PopDiagSft(1))

        ! if we disabled semi-stochastic mode temporarily, reenable it now
        if (tSemiStochastic) call init_semi_stochastic(ss_space_in, tStartedFromCoreGround)

    end subroutine readTimeEvolvedState