Abstract

The basis set dependence of higher-order correlation effects on -type interaction energies was examined by scanning the potential energy surfaces of five dimer systems. The dimers of acetylene (H-CC-H), diacetylene (H-CC-CC-H), cyanogen (NC-CN), diphosphorous (PP), and 1,4-diphosphabutadiyne (PC-CP) were studied in three different configurations: cross, parallel-displaced, and t-shaped. More than 800 potential energy curves (PECs) were generated by computing the interaction energies for all 15 dimer configurations over a range of intermolecular distances with the MP2, coupled-cluster single double (CCSD), and coupled-cluster single double triple (CCSD(T)) methods in conjunction with 21 basis sets ranging from a small 6-31G*(0.25) split-valence basis set to a large aug-cc-pVQZ correlation consistent basis set. Standard extrapolation techniques were also used to construct MP2, CCSD, and CCSD(T) complete basis set (CBS) limit PECs as well as CBS limit higher-order correlation corrections based on the differences between CCSD(T) and MP2 interaction energies, denoted MP 2 CCSD (T), and the corresponding differences between CCSD(T) and CCSD interactions energies, denoted CCSD (T). Double- basis sets struggled to reproduce the former but provided quite reasonable descriptions of the latter as long as diffuse functions were included. The aug-cc-pVDZ basis deviated from the CCSD (T) CBS limit by only 0.06 kcal mol-1 on average and never by more than 0.24 kcal mol-1, whereas the corresponding deviations were approximately twice that for the MP 2 CCSD (T) term. While triple- basis sets typically improved results, only aug-cc-pVTZ provided appreciable improvement over utilizing the aug-cc-pVDZ basis set to compute CCSD CCSD (T). Counterpoise (CP) corrections were also applied to all double- and triple- basis sets, but they rarely yielded a better description of these higher-order correlation effects. CP corrections only consistently improved results when the aug-cc-pVDZ basis set was used to compute MP 2 CCSD (T), yielding mean and maximum absolute deviations from the CBS values of 0.10 and 0.39 kcal mol-1, respectively, for all five dimer systems. © 2012 American Institute of Physics.

Department(s)

Chemistry

Publication Status

Available Access

Comments

National Science Foundation, Grant CHE-0957317

International Standard Serial Number (ISSN)

0021-9606

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2024 American Institute of Physics, All rights reserved.

Publication Date

07 Jan 2012

PubMed ID

22239765

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