dorsal/arxiv
View SchemaTowards standard methods for benchmark quality ab initio thermochemistry --- W1 and W2 theory
| Authors | Jan M. L. Martin, Glenisson de Oliveira |
|---|---|
| Categories | |
| ArXiv ID | physics/9904038 |
| URL | https://arxiv.org/abs/physics/9904038 |
| DOI | 10.1063/1.479454 |
| Journal | Journal of Chemical Physics 111, 1843-1856 (1999) |
Abstract
Two new schemes for computing molecular total atomization energies (TAEs) and/or heats of formation ($\Delta H^\circ_f$) of first-and second-row compounds to very high accuracy are presented. The more affordable scheme, W1 (Weizmann-1) theory, yields a mean absolute error of 0.30 kcal/mol and includes only a single, molecule-independent, empirical parameter. It requires CCSD (coupled cluster with all single and double substitutions) calculations in $spdf$ and $spdfg$ basis sets, while CCSD(T) [i.e. CCSD with a quasiperturbative treatment of connected triple excitations] calculations are only required in $spd$ and $spdf$ basis sets. On workstation computers and using conventional coupled cluster algorithms, systems as large as benzene can be treated, while larger systems are feasible using direct coupled cluster methods. The more rigorous scheme, W2 (Weizmann-2) theory, contains no empirical parameters at all and yields a mean absolute error of 0.23 kcal/mol, which is lowered to 0.18 kcal/mol for molecules dominated by dynamical correlation. It involves CCSD calculations in $spdfg$ and $spdfgh$ basis sets and CCSD(T) calculations in $spdf$ and $spdfg$ basis sets. On workstation computers, molecules with up to three heavy atoms can be treated using conventional coupled cluster algorithms, while larger systems can still be treated using a direct CCSD code. Both schemes include corrections for scalar relativistic effects, which are found to be vital for accurate results on second-row compounds.
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"abstract": "Two new schemes for computing molecular total atomization energies (TAEs)\nand/or heats of formation ($\\Delta H^\\circ_f$) of first-and second-row\ncompounds to very high accuracy are presented. The more affordable scheme, W1\n(Weizmann-1) theory, yields a mean absolute error of 0.30 kcal/mol and includes\nonly a single, molecule-independent, empirical parameter. It requires CCSD\n(coupled cluster with all single and double substitutions) calculations in\n$spdf$ and $spdfg$ basis sets, while CCSD(T) [i.e. CCSD with a\nquasiperturbative treatment of connected triple excitations] calculations are\nonly required in $spd$ and $spdf$ basis sets. On workstation computers and\nusing conventional coupled cluster algorithms, systems as large as benzene can\nbe treated, while larger systems are feasible using direct coupled cluster\nmethods. The more rigorous scheme, W2 (Weizmann-2) theory, contains no\nempirical parameters at all and yields a mean absolute error of 0.23 kcal/mol,\nwhich is lowered to 0.18 kcal/mol for molecules dominated by dynamical\ncorrelation. It involves CCSD calculations in $spdfg$ and $spdfgh$ basis sets\nand CCSD(T) calculations in $spdf$ and $spdfg$ basis sets. On workstation\ncomputers, molecules with up to three heavy atoms can be treated using\nconventional coupled cluster algorithms, while larger systems can still be\ntreated using a direct CCSD code. Both schemes include corrections for scalar\nrelativistic effects, which are found to be vital for accurate results on\nsecond-row compounds.",
"arxiv_id": "physics/9904038",
"authors": [
"Jan M. L. Martin",
"Glenisson de Oliveira"
],
"categories": [
"physics.chem-ph",
"physics.atom-ph"
],
"doi": "10.1063/1.479454",
"journal_ref": "Journal of Chemical Physics 111, 1843-1856 (1999)",
"title": "Towards standard methods for benchmark quality ab initio thermochemistry --- W1 and W2 theory",
"url": "https://arxiv.org/abs/physics/9904038"
},
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