Vibrational computations beyond the harmonic approximation: Performances of the B3LYP density functional for semirigid molecules

• Published in: Journal of computational chemistry Vol. 26; no. 4; pp. 384 - 388
• Main Authors: Carbonniere, Philippe, Lucca, Tecla, Pouchan, Claude, Rega, Nadia, Barone, Vincenzo
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.03.2005; Wiley Subscription Services, Inc; Wiley
• Subjects: B3LYP density functional; basis sets; Chemical Sciences; Computers; Density; Harmonic analysis; hybrid force fields; Molecules; or physical chemistry; Theoretical and; Vibration tests; vibrational frequencies
• ISSN: 0192-8651; 1096-987X
• DOI: 10.1002/jcc.20170

The performances of the B3LYP density functional in the computation of harmonic and anharmonic frequencies were tested using 14 standard basis sets of double and triple zeta quality for a set of semirigid molecules containing from 4 to 12 atoms. The quality of the results is assessed by comparison with the most reliable computations available in the literature. The study reveals that the relatively cheap 6‐31+G(d,p) basis set performs a very good job for harmonic frequency calculations and that B3LYP anharmonicities are in close agreement with the reference values irrespective of the basis set used. On these grounds “hybrid force fields” are proposed to achieve the best compromise between computer time and quality of the results. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 384–388, 2005