The molecular electrostatic potential (MEP) distribution of anisole, chlorobenzene, and fluorobenzene obtained from STO‐3G, 3‐21G, and 6‐31G* basis set ab initio and MNDO and AM1 semiempirical wave functions is investigated to explain the differences among the MEP features obtained for polychlorodibenzo‐p‐dioxins. The main topological features as well as the absoltue and relative minima location obtained from ab initio calculations are independent from the choice of the basis set. MNDO calculations are in good agreement with the ab initio ones in the case of anisole and fluorobenzene, while they incorrectly describe the MEP of chlorobenzene. The AM1 fails to localize the absolute minimum of fluorobenzene and does not find the minimum above the chlorobenzene chlorine atom. The poor agreement of both semiempirical methods with ab initio for any kind of chlorinated compounds is confirmed by results obtained for chloreothylene and chloroethane. We hypothesize that the main problem concerning these methods is that they freeze a too large amount of electrons in the atomic core of elements belonging to the second row, which makes for a wrong description of the core–valence electron interactions. Results obtained by modifying the AM1 parameters related to these interactions confirm our hypothesis

Bonati, L., Cosentino, U., Fraschini, E., Moro, G., Pitea, D. (1992). Molecular electrostatic potentials of substituted aromatic compounds: factors affecting the differences between ab initio and semiempirical results. JOURNAL OF COMPUTATIONAL CHEMISTRY, 13(7), 842-850 [10.1002/jcc.540130708].

Molecular electrostatic potentials of substituted aromatic compounds: factors affecting the differences between ab initio and semiempirical results

BONATI, LAURA;COSENTINO, UGO RENATO;MORO, GIORGIO;PITEA, DEMETRIO
1992

Abstract

The molecular electrostatic potential (MEP) distribution of anisole, chlorobenzene, and fluorobenzene obtained from STO‐3G, 3‐21G, and 6‐31G* basis set ab initio and MNDO and AM1 semiempirical wave functions is investigated to explain the differences among the MEP features obtained for polychlorodibenzo‐p‐dioxins. The main topological features as well as the absoltue and relative minima location obtained from ab initio calculations are independent from the choice of the basis set. MNDO calculations are in good agreement with the ab initio ones in the case of anisole and fluorobenzene, while they incorrectly describe the MEP of chlorobenzene. The AM1 fails to localize the absolute minimum of fluorobenzene and does not find the minimum above the chlorobenzene chlorine atom. The poor agreement of both semiempirical methods with ab initio for any kind of chlorinated compounds is confirmed by results obtained for chloreothylene and chloroethane. We hypothesize that the main problem concerning these methods is that they freeze a too large amount of electrons in the atomic core of elements belonging to the second row, which makes for a wrong description of the core–valence electron interactions. Results obtained by modifying the AM1 parameters related to these interactions confirm our hypothesis
Articolo in rivista - Articolo scientifico
MOLECULAR ELECTROSTATIC POTENTIAL, SEMIEMPIRICAL METHODS
English
842
850
9
Bonati, L., Cosentino, U., Fraschini, E., Moro, G., Pitea, D. (1992). Molecular electrostatic potentials of substituted aromatic compounds: factors affecting the differences between ab initio and semiempirical results. JOURNAL OF COMPUTATIONAL CHEMISTRY, 13(7), 842-850 [10.1002/jcc.540130708].
Bonati, L; Cosentino, U; Fraschini, E; Moro, G; Pitea, D
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/34714
Citazioni
  • Scopus 24
  • ???jsp.display-item.citation.isi??? 23
Social impact