URijkl

This file stores the effectively screened off-centre Coulomb integrals

[math]\displaystyle{ 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}'+{\bf R}) w_{l}^{\sigma'}({\bf r}'+{\bf R}) }[/math]

The format is as follows:

# U_ijkl = [ij,R|kl,0] 
#  I   J   K   L          RE(V_IJKL)          IM(V_IJKL)
# R:    1  0.000000  0.000000  0.000000
   1   1   1   1        4.3457689208        0.0000000000
   2   1   1   1        0.0000021313        0.0000001349
... 
# R:    2  0.000000  0.000000  1.000000
   1   1   1   1        1.2535567886        0.0000000000
   2   1   1   1        0.0324545667       -0.0000455665
 ...

These integrals are written as a post-processing step using ALGO=2e4wa. In contrast to VRijkl, the bare off-centre Coulomb integrals, URijkl is only written if all WFULLxxxx.tmp files commensurate with the selected k-point grid are present in the working directory. The basis set can be set with DMFT_BASIS.

Evaluation of Coulomb integrals can be computationally demanding if the number of basis functions becomes large.

Tip: Use a coarser sub-grid of the original k-point grid with LDOWNSAMPLE for speed up.

Mind: Available as of VASP.6.5.2.

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