dorsal/arxiv
View SchemaThe ground-state spectroscopic constants of Be_2 revisited
| Authors | Jan M. L. Martin |
|---|---|
| Categories | |
| ArXiv ID | physics/9902019 |
| URL | https://arxiv.org/abs/physics/9902019 |
| DOI | 10.1016/S0009-2614(99)00214-6 |
| Journal | Chem. Phys. Lett. 303, 399-407 (1999) |
Abstract
Extensive ab initio calibration calculations combined with extrapolations towards the infinite-basis limit lead to a ground-state dissociation energy of Be_2, D_e=944 \pm 25 1/cm, substantially higher than the accepted experimental value, and confirming recent theoretical findings. Our best computed spectroscopic observables (expt. values in parameters) are G(1)-G(0)=223.7 (223.8), G(2)-G(1)=173.8 (169 \pm 3), G(3)-G(2)=125.4 (122 \pm 3), and B_0=0.6086 (0.609) 1/cm; revised spectroscopic constants are proposed. Multireference calculations based on a full valence CAS(4/8) reference suffer from an unbalanced description of angular correlation; for the utmost accuracy, a CAS(4/16) reference including the $(3s,3p)$ orbitals is required, while for less accurate work a CAS(4/4) reference is recommended. The quality of computed coupled cluster results depends crucially on the description of connected triple excitations; the CC5SD(T) method yields unusually good results because of an error compensation.
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"abstract": "Extensive ab initio calibration calculations combined with extrapolations\ntowards the infinite-basis limit lead to a ground-state dissociation energy of\nBe_2, D_e=944 \\pm 25 1/cm, substantially higher than the accepted experimental\nvalue, and confirming recent theoretical findings. Our best computed\nspectroscopic observables (expt. values in parameters) are G(1)-G(0)=223.7\n(223.8), G(2)-G(1)=173.8 (169 \\pm 3), G(3)-G(2)=125.4 (122 \\pm 3), and\nB_0=0.6086 (0.609) 1/cm; revised spectroscopic constants are proposed.\nMultireference calculations based on a full valence CAS(4/8) reference suffer\nfrom an unbalanced description of angular correlation; for the utmost accuracy,\na CAS(4/16) reference including the $(3s,3p)$ orbitals is required, while for\nless accurate work a CAS(4/4) reference is recommended. The quality of computed\ncoupled cluster results depends crucially on the description of connected\ntriple excitations; the CC5SD(T) method yields unusually good results because\nof an error compensation.",
"arxiv_id": "physics/9902019",
"authors": [
"Jan M. L. Martin"
],
"categories": [
"physics.chem-ph",
"physics.atm-clus"
],
"doi": "10.1016/S0009-2614(99)00214-6",
"journal_ref": "Chem. Phys. Lett. 303, 399-407 (1999)",
"title": "The ground-state spectroscopic constants of Be_2 revisited",
"url": "https://arxiv.org/abs/physics/9902019"
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