UIJKL

This file stores the effectively screened Coulomb integrals

$U_{ijkl}^{\sigma\sigma'} = \int {\rm d}{\bf r}\int {\rm d}{\bf r}' w_{i}^{*\sigma}({\bf r}) w_{j}^{\sigma}({\bf r}) U({\bf r},{\bf r}',\omega) w_{k}^{*\sigma'}({\bf r}') w_{l}^{\sigma'}({\bf r}')$

in following format

# U_ijkl = [ij,R|kl,0] 
#  I   J   K   L          RE(V_IJKL)          IM(V_IJKL)
   1   1   1   1        4.3457689208        0.0000000000
   2   1   1   1        0.0000021313        0.0000001349
...

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