Journal ArticleDOI
The alkaline earth dimer cations (Be2 +, Mg2 +, Ca2 +, Sr2 +, and Ba2 +). Coupled cluster and full configuration interaction studies†
Huidong Li,Hao Feng,Weiguo Sun,Yi Zhang,Qunchao Fan,Kirk A. Peterson,Yaoming Xie,Henry F. Schaefer +7 more
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In this article, both coupled cluster and full configuration interaction methods were used to describe the M2+ systems and the results for the unknown dissociation energies were obtained for the neutral alkaline earth dimers.Abstract:
Although all of the neutral alkaline earth dimers have been studied experimentally, only for the beryllium and strontium systems have the diatomic radical cations been subjected to modern spectroscopic techniques. In the present research, both coupled cluster and full configuration interaction methods were used to describe the M2 + systems. Basis sets as large as aug-cc-pCV5Z were chosen. For both Be2 + and Sr2 + agreement with the experiments is outstanding. Final predictions for the unknown dissociation energies are 10,651 (Mg2 +), 9605 (Ca2 +), and 8980 cm−1 (Ba2 +). The M2 + dissociation energies decrease monotonically going down the periodic except for the Sr2 + - Ba2 + pair. The unknown bond distances re are 3.015 (Mg2 +), 3.814 (Ca2 +), 4.194 (Sr2 +), and 4.587 A (Ba2 +).read more
Citations
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Automatic Generation of Auxiliary Basis Sets
TL;DR: A procedure was developed to automatically generate auxiliary basis sets (ABSs) for use with the resolution of the identity (RI) approximation, starting from a given orbital basis set (OBS).
Journal ArticleDOI
Cold hybrid ion-atom systems
Michał Tomza,Krzysztof Jachymski,Rene Gerritsma,Antonio Negretti,Tommaso Calarco,Zbigniew Idziaszek,Paul S. Julienne +6 more
TL;DR: In this paper, a review of the theoretical and experimental progress in research on cold hybrid ion-atom systems which aim to combine the best features of the two well-established fields is provided.
Journal ArticleDOI
Gaussian basis sets for use in correlated molecular calculations. XI. Pseudopotential-based and all-electron relativistic basis sets for alkali metal (K–Fr) and alkaline earth (Ca–Ra) elements
J. Grant Hill,Kirk A. Peterson +1 more
TL;DR: Not surprisingly, it is found that outer-core correlation is vital for accurate calculation of the thermodynamic and spectroscopic properties of diatomic molecules containing these elements.
Journal ArticleDOI
Improved accuracy benchmarks of small molecules using correlation consistent basis sets
TL;DR: In this article, the convergence of the 1-particle expansion was achieved through use of correlation consistent basis sets as large as aug-cc-pV8Z and aug-mcc-mV9Z, followed by the application of a simple extrapolation formula in order to more closely approximate the basis set limit.
Journal ArticleDOI
The nature of the chemical bond in Be2+, Be2, Be2-, and Be3.
TL;DR: Previous findings are rationalized and put them in a unified context of what and why should be done in similar hard to crack cases to unveil their bonding pattern.
References
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Journal ArticleDOI
Basis-set convergence of correlated calculations on water
TL;DR: In this paper, the basis-set convergence of the electronic correlation energy in the water molecule is investigated at the second-order Mo/ller-Plesset level and at the coupled-cluster singles-and-doubles level with and without perturbative triples corrections applied.
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Psi4: an open-source ab initio electronic structure program
Justin M. Turney,Andrew C. Simmonett,Robert M. Parrish,Edward G. Hohenstein,Francesco A. Evangelista,Justin T. Fermann,Benjamin Mintz,Lori A. Burns,Jeremiah J. Wilke,Micah L. Abrams,Nicholas J. Russ,Matthew L. Leininger,Curtis L. Janssen,Edward T. Seidl,Wesley D. Allen,Henry F. Schaefer,Rollin A. King,Edward F. Valeev,C. David Sherrill,T. Daniel Crawford +19 more
TL;DR: The Psi4 program is a new approach to modern quantum chemistry, encompassing Hartree–Fock and density‐functional theory to configuration interaction and coupled cluster and offers flexible user input built on the Python scripting language that enables both new and experienced users to make full use of the program's capabilities.
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Gaussian basis sets for use in correlated molecular calculations. VII. Valence, core-valence, and scalar relativistic basis sets for Li, Be, Na, and Mg
TL;DR: Correlation consistent basis sets for the alkali and alkaline earth metals Li, Be, Na, and Mg have been developed, including the valence (cc-pVnZ), augmented valence and weighted core-valence (c-pwCVnZ) basis sets as discussed by the authors.
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An electron pair operator approach to coupled cluster wave functions. Application to He2, Be2, and Mg2 and comparison with CEPA methods
TL;DR: In this article, a method for obtaining coupled cluster expansions with double substitutions (CCD) utilizing the electron pair operator approach of self-consistent electron pair (SCEP) theory is presented.
Journal ArticleDOI
Beryllium Dimer—Caught in the Act of Bonding
TL;DR: High-resolution spectroscopy maps out the unusual ground state electronic potential of the beryllium dimer, a deceptively simple molecule that, in spite of having only eight electrons, poses difficult challenges for ab initio quantum chemical methods.