Abstract

A series of two-layer ONIOM (MO:MO) methods have been systematically applied to two biologically important hydrogen-bonded dimers. Single conformations of the serine-water dimer and of the threonine-water dimer were optimized with the MP2 technique and a DZP++ basis set. The counterpoise corrected and uncorrected dissociation energies of the dimers were then computed with RHF, B3LYP, MP2, and CCSD(T) electronic structure techniques with 3-21G, 6-31+G(d), and DZP++ basis sets as well as every possible two-layer ONIOM permutation using either CCSD(T)/DZP++ or MP2/DZP++ as the high-level method. To judge the performance of each technique, the data are compared to results obtained with the CCSD(T) method and a double-zeta basis set with diffuse and polarization functions on all atoms [the largest basis set for which CCSD(T) computations were feasible]. MP2 theory reproduces the target CCSD(T) data extremely well. ONIOM schemes that employ model systems including the sidechain and α-carbon perform well, introducing errors of less than 0.21 kcal/mol. We observe that MP2:RHF approaches that use this large model system require almost the same CPU time as a B3LYP computation on the entire system but are far more accurate. Guidelines are presented for the application of two-layer ONIOM methods to hydrogen bonding between similar functional groups in larger biologic systems. © 2003 Wiley Periodicals, Inc.

Department(s)

Chemistry

Publication Status

Full Access

Keywords and Phrases

Hydrogen bonding; Integrated methods; ONIOM

International Standard Serial Number (ISSN)

0020-7608

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 Wiley, All rights reserved.

Publication Date

05 Feb 2004

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