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Validating additive correction schemes against gradient‐based extrapolations
Author(s) -
Kraus Peter,
Frank Irmgard
Publication year - 2019
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.25953
Subject(s) - extrapolation , perturbation theory (quantum mechanics) , basis (linear algebra) , statistical physics , coupled cluster , quantum chemistry , computational chemistry , computer science , algorithm , mathematics , chemistry , molecule , physics , quantum mechanics , mathematical analysis , geometry , supramolecular chemistry
The use of additive correction schemes to obtain structures and vibrational frequencies of increasingly larger molecules is becoming more common. Such approaches, based on the cubic extrapolation formula applied directly to the quantity of interest, have been successfully validated only at the highest levels of computational accuracy: for coupled cluster methods with comparably large basis sets. Here, a systematic validation of geometries and vibrational frequencies is carried out, including more affordable and relevant levels of theory, such as the Møller‐Plesset perturbation theory applied with smaller basis sets. Comparisons of such additive schemes against the more rigorous gradient‐based extrapolation are presented. The cbs () routine of the open‐source quantum‐chemistry package Psi4 has been extended for this purpose. The results confirm that geometries and frequencies of covalently bound species obtained with additive correction schemes are in an excellent agreement with the results of gradient‐based extrapolations. However, when applied to systems involving noncovalent interactions, the errors due to such schemes are significantly larger. In general, we propose the application of gradient‐based extrapolations, as they incur no extra cost compared to additive schemes.