Interfragment interactions

Approximate transferability of fuzzy density fragments is a key feature of the method, where the fuzzy fragments are custom-made in order to reproduce interfragment interactions. By increasing the size of the interaction shell about each fuzzy density fragment, the error of transferred fragment densities can be reduced below any positive threshold. One tool for this purpose is the Adjustable Density... 

Because of the necessity to take into account the interfragment interaction, the method for obtaining a valid expression in the general case for D(p, q, qB) is not obvious. Un-... 

The pathway to chrysenes, in this case, was assumed to include the formation of dimeric salts 268. Then the intramolecular interfragment interaction takes place with the formation of the C4b—CiA bond, which leads to the already familiar intermediate 272 (Scheme 14). 

Contrary to a-1 dimers 269, the 4-1 dimers 276 are more susceptible toward regenerating the starting 2-benzopyrylium salts in acidic media. However, under special conditions, one can carry out some transformations of dimers 276 determined by their interfragment interactions. Thus, thermolysis of dimer 281 with catalytic amounts of acetic acid results in the naphthalene derivative 287. This compound, together with another naphthalene derivative 285, is also formed from semiacetal 284 on heating in acetic acid [90KGS(ip3)]. 

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