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A simplex optimized INDO calculation of 13 C chemical shifts in hydrocarbons
Author(s) -
Chesnut D. B.,
Whitehurst F. W.
Publication year - 1980
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.540010105
Subject(s) - simplex , simplex algorithm , yield (engineering) , chemistry , hartree–fock method , ab initio , approximation error , molecule , chemical shift , computational chemistry , atomic physics , physics , thermodynamics , mathematics , algorithm , combinatorics , organic chemistry , linear programming
The variable‐size simplex optimization method is used to reparametrize the I + A and β parameters of an INDO approximation to the perturbed Hartree–Fock calculation of 13 C chemical shifts in hydrocarbons. The absolute shifts for 39 nuclei in a set of molecules containing up to four carbons are reproduced within a standard error of 9.9 ppm for an unconstrained optimization and to a standard error of 10.0 ppm for an optimization constrained to yield gross atomic charges in agreement with double‐zeta ab initio calculations.