A series of issue are present in the input file.
1) An ECP section is missing for I and U (that's why you are getting weird results in your starting guess. Once you supply the ECP section, starting guess problems will vanish)
https://nwchemgit.github.io/ECP.html2) The SCF section is irrelevant for a dft task. This is the reason for ignoring the "input hcore" directive.
3) I would recommend adding "start" to the beginning of the input file since the default is restart
start
title "UO2I2(OH2)2 - DFT Single Point Restart"
geometry units angstroms
U 0.00000000 0.00000000 0.00000000
O 0.00000000 0.00000000 1.77300000
O 0.00000000 0.00000000 -1.77300000
I 0.00000000 -3.02670000 0.00000000
I 0.00000000 3.02670000 0.00000000
O 2.31800000 0.00000000 0.00000000
O -2.31800000 0.00000000 0.00000000
H 2.65790000 -0.74870000 0.05000000
H 2.65790000 0.74870000 -0.05000000
H -2.65790000 -0.74870000 -0.05000000
H -2.65790000 0.74870000 0.05000000
end
basis spherical
U library stuttgart_rlc_ecp
I library stuttgart_rlc_ecp
O library 6-31G*
H library 6-31G*
end
ecp
U library stuttgart_rlc_ecp
I library stuttgart_rlc_ecp
end
dft
vectors input atomic output uo2i2water2
xc b3lyp
iterations 100
convergence energy 1e-6 density 1e-5 gradient 5e-4
end
task dft energy