Bikash
As mentioned in https://github.com/nwchemgit/nwchem/issues/7
nwchem 6.8 contains bugs in the molden feature of task property (bugs fixed in the upcoming 6.8.1 release)
As mentioned in the URL above, a workaround for 6.8 is to use "molden" keyword in dft section and perform just a dft energy task.
This means for your input
dft
xc slater perdew81
...
molden
end
set molden:do_norm_janpa t
task dft energy