I believe you need to .f file as a parameter, not as a command-single-string. same with the "--domain "+i, which i would split in two elements of the list.
Assuming that:
FORTRAN executable, ~/ is indeed the correct way for the FORTRAN executableI would change this line:
subprocess.Popen(["FORTRAN ~/C:/Users/Vishnu/Desktop/Fortran_Program_Rum/phase1.f", "--domain "+i])
to
subprocess.Popen(["FORTRAN", "~/C:/Users/Vishnu/Desktop/Fortran_Program_Rum/phase1.f", "--domain", i])
If that doesn't work, you should do a os.path.exists() for the .f file, and check that you can launch the FORTRAN executable without any path, and set the path or system path variable accordingly
[EDIT 6-Mar-2017]
As the exception, detailed in the original post, is a python exception from subprocess; it is likely that the WinError 2 is because it cannot find FORTRAN
I highly suggest that you specify full path for your executable:
for i in input:
exe = r'c:\somedir\fortrandir\fortran.exe'
fortran_script = r'~/C:/Users/Vishnu/Desktop/Fortran_Program_Rum/phase1.f'
subprocess.Popen([exe, fortran_script, "--domain", i])
if you need to convert the forward-slashes to backward-slashes, as suggested in one of the comments, you can do this:
for i in input:
exe = os.path.normcase(r'c:\somedir\fortrandir\fortran.exe')
fortran_script = os.path.normcase(r'~/C:/Users/Vishnu/Desktop/Fortran_Program_Rum/phase1.f')
i = os.path.normcase(i)
subprocess.Popen([exe, fortran_script, "--domain", i])
[EDIT 7-Mar-2017]
The following line is incorrect:
exe = os.path.normcase(r'~/C:/Program Files (x86)/Silverfrost/ftn95.exe'
I am not sure why you have ~/ as a prefix for every path, don't do that.
for i in input:
exe = os.path.normcase(r'C:/Program Files (x86)/Silverfrost/ftn95.exe'
fortran_script = os.path.normcase(r'C:/Users/Vishnu/Desktop/Fortran_Program_Rum/phase1.f')
i = os.path.normcase(i)
subprocess.Popen([exe, fortran_script, "--domain", i])
[2nd EDIT 7-Mar-2017]
I do not know this FORTRAN or ftn95.exe, does it need a shell to function properly?, in which case you need to launch as follows:
subprocess.Popen([exe, fortran_script, "--domain", i], shell = True)
You really need to try to launch the command manually from the working directory which your python script is operating from. Once you have the command which is actually working, then build up the subprocess command.