The generalized identification of truly interfacial molecules (ITIM) algorithm for nonplanar interfaces

Marcello Sega, Sofia S Kantorovich, Pal Jedlovszky, Miguel Jorge

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We present a generalized version of the ITIM algorithm for the identification of interfacial molecules, which is able to treat arbitrarily shaped interfaces. The algorithm exploits the similarities between the concept of probe sphere used in ITIMand the circumsphere criterion used in the α-shapes approach, and can be regarded either as a reference-frame independent version of the former, or as an extended version of the latter that includes the atomic excluded volume. The new algorithm is applied to compute the intrinsic orientational order parameters of water around a dodecylphosphocholine and a cholic acid micelle in aqueous environment, and to the identification of solvent-reachable sites in four model structures for soot. The additional algorithm introduced for the calculation of intrinsic density profiles in arbitrary geometries proved to be extremely useful also for planar interfaces, as it allows to solve the paradox of smeared intrinsic profiles far from the interface.
Original languageEnglish
Article number044110
Number of pages10
JournalJournal of Chemical Physics
Issue number4
Publication statusPublished - 28 Jan 2013


  • micelles
  • interfacial molecules
  • planar interfaces

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