Study of locally dense and locally saturated basis sets in localized molecular orbital calculations of nuclear shielding: Ab initio LORG calculations for 13C and 17O in norbornenone
✍ Scribed by Robert A. Kirby; Aage E. Hansen
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 564 KB
- Volume
- 57
- Category
- Article
- ISSN
- 0020-7608
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✦ Synopsis
This study demonstrates the use of uneven atomic basis sets for ab initio calculations of NMR shielding in the localized orbital/local origin (LORG) approach with norbornenone as the test case. We distinguish between locally dense sets (extended basis on target atom only) and locally saturated sets (extended bases on target atom and atoms in its first bonding sphere), using 6-311~** and 6 -3 1 ~ sets to describe the high and low level of function sets. It is shown that the use of these uneven sets can simulate high basis set level calculations of shieldings for 'H and for all the I3C nuclei in this molecule and, hence, allows quite accurate ab initio calculations of shielding properties of these nuclei in large molecules using relatively modest computational facilities. The shielding of the double-bonded "0 nucleus is apparently sensitive to basis-set quality beyond the first bonding sphere.