dorsal/arxiv
View SchemaA fully ab initio quartic force field of spectroscopic quality for SO_3
| Authors | Jan M. L. Martin |
|---|---|
| Categories | |
| ArXiv ID | physics/9808012 |
| URL | https://arxiv.org/abs/physics/9808012 |
| DOI | 10.1016/S1386-1425(98)00271-6 |
| Journal | Spectrochimica Acta A 55, 713-722 (1999) |
Abstract
The quartic force field of SO$_3$ was computed fully ab initio using coupled cluster (CCSD(T)) methods and basis sets of up to $spdfgh$ quality. The effect of inner-shell correlation was taken into account. The addition of tight $d$ functions is found to be essential for accurate geometries and harmonic frequencies. The equilibrium geometry and vibrational fundamentals are reproduced to within 0.0003 \AA and (on average) 1.15 cm^{-1}, respectively. We recommend the following revised values for the harmonic frequencies: $\omega_1 = 1082.7, \omega_2 = 502.6, \omega_3 = 1415.4, \omega_4 = 534.0 cm^{-1}$. In addition, we have shown that the addition of inner polarization functions to second-row elements is highly desirable even with more approximate methods like B3LYP, and greatly improves the quality of computed geometries and harmonic frequencies of second-row compounds at negligible extra computational cost. For larger such molecules, the B3LYP/VTZ+1 level of theory should be a very good compromise between accuracy and computational cost.
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"abstract": "The quartic force field of SO$_3$ was computed fully ab initio using coupled\ncluster (CCSD(T)) methods and basis sets of up to $spdfgh$ quality. The effect\nof inner-shell correlation was taken into account. The addition of tight $d$\nfunctions is found to be essential for accurate geometries and harmonic\nfrequencies. The equilibrium geometry and vibrational fundamentals are\nreproduced to within 0.0003 \\AA and (on average) 1.15 cm^{-1}, respectively. We\nrecommend the following revised values for the harmonic frequencies: $\\omega_1\n= 1082.7, \\omega_2 = 502.6, \\omega_3 = 1415.4, \\omega_4 = 534.0 cm^{-1}$. In\naddition, we have shown that the addition of inner polarization functions to\nsecond-row elements is highly desirable even with more approximate methods like\nB3LYP, and greatly improves the quality of computed geometries and harmonic\nfrequencies of second-row compounds at negligible extra computational cost. For\nlarger such molecules, the B3LYP/VTZ+1 level of theory should be a very good\ncompromise between accuracy and computational cost.",
"arxiv_id": "physics/9808012",
"authors": [
"Jan M. L. Martin"
],
"categories": [
"physics.chem-ph"
],
"doi": "10.1016/S1386-1425(98)00271-6",
"journal_ref": "Spectrochimica Acta A 55, 713-722 (1999)",
"title": "A fully ab initio quartic force field of spectroscopic quality for SO_3",
"url": "https://arxiv.org/abs/physics/9808012"
},
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