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A physically meaningful method for the comparison of potential energy functions
Author(s) -
Alonso José Luis,
Echenique Pablo
Publication year - 2005
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20337
Subject(s) - van der waals force , ramachandran plot , standard deviation , additive function , measure (data warehouse) , root mean square , ab initio , statistical physics , energy (signal processing) , meaning (existential) , absolute deviation , mean absolute error , mean squared error , mathematics , thermodynamics , chemistry , statistics , computer science , physics , protein structure , molecule , mathematical analysis , quantum mechanics , data mining , biochemistry , psychotherapist , psychology
In the study of the conformational behavior of complex systems, such as proteins, several related statistical measures are commonly used to compare two different potential energy functions. Among them, the Pearson's correlation coefficient r has no units and allows only semiquantitative statements to be made. Those that do have units of energy and whose value may be compared to a physically relevant scale, such as the root‐mean‐square deviation (RMSD), the mean error of the energies (ER), the standard deviation of the error (SDER) or the mean absolute error (AER), overestimate the distance between potentials. Moreover, their precise statistical meaning is far from clear. In this article, a new measure of the distance between potential energy functions is defined that overcomes the aforementioned difficulties. In addition, its precise physical meaning is discussed, the important issue of its additivity is investigated, and some possible applications are proposed. Finally, two of these applications are illustrated with practical examples: the study of the van der Waals energy, as implemented in CHARMM, in the Trp‐Cage protein (PDB code 1L2Y) and the comparison of different levels of the theory in the ab initio study of the Ramachandran map of the model peptide HCO‐L‐Ala‐NH 2 . © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 238–252, 2006