### Abstract

Both electron correlation and basis set effects are important in the description of the bond in Be_{2}. We apply a new version of the multireference averaged quadratic coupled-cluster method which is an approximately size extensive modification of the multireference configuration interaction method and was shown to yield potential energy surfaces parallel to full-CI ones. We show this in the case of Be_{2} as well. Since the method is considerably cheaper than full-CI, we were able to account for core correlation and calculate the whole potential energy surface. Equilibrium geometry, vibrational frequencies and dissociation energy are obtained. For the former two quantities the experimental data are confirmed by the calculations, while the results suggest that the dissociation energy might be considerably higher than the one obtained from the lowest vibrational frequencies. Special attention is paid to the basis set superposition error. Our best calculation of the dissociation energy D_{e} is 864 cm^{-1} which is considered to be a lower bound.

Original language | English |
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Pages (from-to) | 400-408 |

Number of pages | 9 |

Journal | Chemical Physics Letters |

Volume | 258 |

Issue number | 3-4 |

Publication status | Published - Aug 16 1996 |

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### ASJC Scopus subject areas

- Physical and Theoretical Chemistry
- Spectroscopy
- Atomic and Molecular Physics, and Optics

### Cite this

**High-quality theoretical potential energy surface for Be _{2} by using the multireference averaged quadratic coupled-cluster (MR-AQCC) method and large basis sets.** / Füsti-Molnár, László; Szalay, P.

Research output: Contribution to journal › Article

_{2}by using the multireference averaged quadratic coupled-cluster (MR-AQCC) method and large basis sets',

*Chemical Physics Letters*, vol. 258, no. 3-4, pp. 400-408.

_{2}by using the multireference averaged quadratic coupled-cluster (MR-AQCC) method and large basis sets. Chemical Physics Letters. 1996 Aug 16;258(3-4):400-408.

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TY - JOUR

T1 - High-quality theoretical potential energy surface for Be2 by using the multireference averaged quadratic coupled-cluster (MR-AQCC) method and large basis sets

AU - Füsti-Molnár, László

AU - Szalay, P.

PY - 1996/8/16

Y1 - 1996/8/16

N2 - Both electron correlation and basis set effects are important in the description of the bond in Be2. We apply a new version of the multireference averaged quadratic coupled-cluster method which is an approximately size extensive modification of the multireference configuration interaction method and was shown to yield potential energy surfaces parallel to full-CI ones. We show this in the case of Be2 as well. Since the method is considerably cheaper than full-CI, we were able to account for core correlation and calculate the whole potential energy surface. Equilibrium geometry, vibrational frequencies and dissociation energy are obtained. For the former two quantities the experimental data are confirmed by the calculations, while the results suggest that the dissociation energy might be considerably higher than the one obtained from the lowest vibrational frequencies. Special attention is paid to the basis set superposition error. Our best calculation of the dissociation energy De is 864 cm-1 which is considered to be a lower bound.

AB - Both electron correlation and basis set effects are important in the description of the bond in Be2. We apply a new version of the multireference averaged quadratic coupled-cluster method which is an approximately size extensive modification of the multireference configuration interaction method and was shown to yield potential energy surfaces parallel to full-CI ones. We show this in the case of Be2 as well. Since the method is considerably cheaper than full-CI, we were able to account for core correlation and calculate the whole potential energy surface. Equilibrium geometry, vibrational frequencies and dissociation energy are obtained. For the former two quantities the experimental data are confirmed by the calculations, while the results suggest that the dissociation energy might be considerably higher than the one obtained from the lowest vibrational frequencies. Special attention is paid to the basis set superposition error. Our best calculation of the dissociation energy De is 864 cm-1 which is considered to be a lower bound.

UR - http://www.scopus.com/inward/record.url?scp=0030590154&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030590154&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0030590154

VL - 258

SP - 400

EP - 408

JO - Chemical Physics Letters

JF - Chemical Physics Letters

SN - 0009-2614

IS - 3-4

ER -