This page shows how to calculate U - function. There is an simple example of calculation U -function for simple CH5N molecule below. Here are input files.
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CH5N.bas
7 7 1.763266 0.773353 -0.259722 6 0.474220 0.075638 -0.015967 1 2.595372 0.133817 -0.297809 1 2.017882 1.470682 0.480907 1 0.229708 -0.640655 -0.836563 1 -0.382559 0.790390 0.018898 1 0.401767 -0.518300 0.926463
Calculation of U-function is turned on by iu = 1 in fireball.in.
fireball.in
&OPTION basisfile = CH5N.bas icluster = 1 nstepf = 1 T_initial = 100.0 T_final = 100.0 sigmatol = 0.000000001 dt = 0.01 iquench = 0 max_scf_iterations = 200 iu = 1 &END &OUTPUT iwrteigen = 1 iwrtxyz = 1 iwrtefermi = 1 &END
Next you need input file u.inp, where you have to write total number of electron. You can choose molecular orbitals for which you want to calculate U. There are 5 orbitals (6,7,8,10,22) in this case. u.inp
14 ! number of electrons 5 ! number of orbitals 6 ! states number 7 8 10 22
The output file is called u_func.dat, where is written number of selected orbital in the first column and in the second one are u values.
6 2.1590 7 2.3341 8 1.9742 10 1.9721 22 1.4045