program exporttest

implicit none

integer(8), parameter :: Stot= 2
integer(8), dimension(:), allocatable :: Nfp, Nf, Nfvp, Nfv
integer(4) :: rank, s
character(10) :: rankstring, sstring
character(*), parameter :: datadir= '/Users/robertalbarran/Desktop/DISSERTATION/DSMCDATA/'
character(50) :: NfTfile

type Specietype
    integer(8), dimension(:), allocatable :: NfT, NfvT
end type Specietype
type(Specietype), dimension(:), allocatable :: SpecieT

allocate(SpecieT(Stot))
allocate(Nfp(Stot), Nfvp(Stot))
allocate(SpecieT(Stot)%NfT(1), SpecieT(Stot)%NfvT(1))
rank= 0

! import data

do s= 1, Stot, 1
    write(sstring, '(I5)') s
    allocate(Nf(1))

    open (unit= 0, file= datadir // adjustl(adjustr(sstring) // ':' // 'Nfmat.bin'), &
    status= 'old', form= 'unformatted', access= 'stream')
    read(0) Nfp(s)
    close(0)

    Nf(1)= Nfp(s)
    SpecieT(s)%NfT= Nf

    deallocate(Nf)
end do
deallocate(Nfp)

write(*, *) 'NfT s1= ', SpecieT(1)%NfT(1)
write(*, *) 'NfT s2= ', SpecieT(2)%NfT(1)

! export data

write(rankstring, '(i10)')  rank

do s= 1, Stot, 1
    write(sstring, '(I5)') s

    NfTfile= &
    datadir // adjustl(adjustr(rankstring) // ':' // &
    adjustl(adjustr(sstring) // ':' // 'NfTfort.bin'))
    open(unit= 0, status= 'replace', file= NfTfile, form= 'unformatted', &
    access= 'stream')
    write(0) SpecieT(s)%NfT
    close(0)

end do

! import exported data

do s= 1, Stot, 1
    write(sstring, '(I5)') s
    allocate(Nfv(1))

    open (unit= 0, file= datadir // adjustl(adjustr(rankstring) // ':' // &
    adjustl(adjustr(sstring) // ':' // 'NfTfort.bin')), &
    status= 'old', form= 'unformatted', access= 'stream')
    read(0) Nfvp(s)
    close(0)

    Nfv(1)= Nfvp(s)
    SpecieT(s)%NfvT= Nfv

    deallocate(Nfv)
end do
deallocate(Nfvp)

write(*, *) 'NfvT s1= ', SpecieT(1)%NfvT(1)
write(*, *) 'NfvT s2= ', SpecieT(2)%NfvT(1)

end program exporttest

NfT s1=                     1
NfT s2=                     1
At line 68 of file exporttest.f90
Fortran runtime error: Cannot open file '/Users/robertalbarran/Desktop/DISSERTATION/DSMCDATA/0:1:NfTfort.bin': No such file or directory

Error termination. Backtrace:
#0  0x1052bee46
#1  0x1052bf718
#2  0x1052bfd7c
#3  0x10534005a
#4  0x1053406e3
#5  0x1050c59de
#6  0x1050c5c5e