Electric fields in ab-initio treatment of polar crystals

ELECTRIC FIELDS IN AB INITIO TREATMENTS OF POLAR CRYSTALS 

There is still a limit to the all-embracing power of the self-consistent schemes macroscopic electric fields. a consequence of perioc city of the crystal, the relation V(r + 

The classical theories meet difficulties, as well, when it comes to dealing with k=0 macroscopic fields, an the usual procedure In that case is to evaluate limits for k - 0. This approach is not viable in the se -ggnslstent procedures - although attempts have been made recently to find out how to circumvent the problem of non-periodicity. 

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