Adiabatic electron affinities of PF5 and SF6: a coupled-cluster study

1998 ◽  
Vol 94 (1) ◽  
pp. 121-125 ◽  
Author(s):  
Gennady GUTSEV ◽  
RODNEY BARTLETT
Keyword(s):  
Coupled Cluster ◽  
Electron Affinities

Application of multireference linearized coupled-cluster theory to atomic and molecular systems

2018 ◽  
Vol 17 (02) ◽  
pp. 1850016 ◽  
Author(s):  
Jiang Yi ◽  
Feiwu Chen
Keyword(s):  
Ground State ◽  
Basis Sets ◽  
Coupled Cluster ◽  
Vibration Frequencies ◽  
Electron Affinities ◽  
Proton Affinities ◽  
Coupled Cluster Theory ◽  
Molecular Systems ◽  
Ground State Energies ◽  
Second Order Perturbation Theory

Applications of the multireference linearized coupled-cluster single-doubles (MRLCCSD) to atomic and molecular systems have been carried out. MRLCCSD is exploited to calculate the ground-state energies of HF, H2O, NH3, CH4, N2, BF, and C2with basis sets, cc-pVDZ, cc-pVTZ and cc-pVQZ. The equilibrium bond lengths and vibration frequencies of HF, HCl, Li2, LiH, LiF, LiBr, BH, and AlF are computed with MRLCCSD and compared with the experimental data. The electron affinities of F and CH as well as the proton affinities of H2O and NH3are also calculated with MRLCCSD. These results are compared with the results produced with second-order perturbation theory, linearized coupled-cluster doubles (LCCD), coupled-cluster doubles (CCD), coupled-cluster singles and doubles (CCSD), CCSD with perturbative triples correction (CCSD(T)). It is shown that all results obtained with MRLCCSD are reliable and accurate.

Coupled Cluster Studies of Ionization Potentials and Electron Affinities of Single-Walled Carbon Nanotubes

2017 ◽  
Vol 121 (6) ◽  
pp. 1328-1335 ◽  
Author(s):  
Bo Peng ◽  
Niranjan Govind ◽  
Edoardo Aprà ◽  
Michael Klemm ◽  
Jeff R. Hammond ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Single Walled Carbon Nanotubes ◽  
Ionization Potentials ◽  
Coupled Cluster ◽  
Electron Affinities ◽  
Single Walled Carbon ◽  
Walled Carbon Nanotubes

Electron Affinities of BN, NO and NF: Coupled Cluster and Multireference Configuration Interaction Calculations

2005 ◽  
Vol 70 (7) ◽  
pp. 923-940 ◽  
Author(s):  
Jiří Fišer ◽  
Rudolf Polák
Keyword(s):  
Configuration Interaction ◽  
Relativistic Effects ◽  
Basis Set ◽  
Basis Sets ◽  
Spectroscopic Constants ◽  
Coupled Cluster ◽  
Electron Affinities ◽  
Complete Basis Set ◽  
Correlation Consistent ◽  
Consistent Basis

The accurate adiabatic electron affinities (EA) of the BN, NO and NF molecules have been determined using the coupled cluster approach and multireference configuration interaction methods. By combining large doubly augmented correlation-consistent basis sets (through the sextuple zeta) and complete basis set extrapolations with corrections for core-valence correlation and relativistic effects, we find that the RCCSD(T) method gives EA(BN) = 3.153 eV in very close agreement with experiment and predicts EA(NF) = 0.247 eV. The RCCSD(T) and UCCSD(T) EA(NO) results, 0.008 and 0.031 eV, bracket the experimental value. For both the neutral and anionic ground state species the usual spectroscopic constants were derived.

scholarly journals Three-Body Excitations in Fock-Space Coupled-Cluster: Fourth Order Perturbation Correction to Electron Affinity and Its Relation to Bondonic Formalism

2021 ◽  
Vol 22 (16) ◽  
pp. 8953
Author(s):  
Suhita Basumallick ◽  
Mihai V. Putz ◽  
Sourav Pal
Keyword(s):  
Fourth Order ◽  
Electron Affinity ◽  
Fock Space ◽  
Direct Calculation ◽  
Basis Set ◽  
Basis Sets ◽  
Coupled Cluster ◽  
Electron Affinities ◽  
Computationally Efficient ◽  
Order Scheme

In this paper, we present a formulation of highly correlated Fock-space multi-reference coupled-cluster (FSMRCC) methods, including approximate triples on top of the FSMRCC with singles and doubles, which correct the electron affinities by at least at third and up to the fourth order in perturbation. We discuss various partial fourth-order schemes, which are reliable and yet computationally more efficient than the full fourth-order triples scheme. The third-order scheme is called MRCCSD+. We present two approximate fourth-order schemes, MRCCSD+ and MRCCSD+. The results that are presented allow one to choose an appropriate fourth-order scheme, which is less expensive and right for the problem. All these schemes are based on the effective Hamiltonian scheme, and provide a direct calculation of the vertical electron affinities. We apply these schemes to a prototype molecule, using four different basis sets, as well as BeO and CH+. We have calculated the vertical electron affinities of at the geometry of the neutral molecule. We also present the vertical ionization potentials of the anion at the geometry of the anion ground state. We have also shown how to calculate adiabatic electron affinity, though in that case we lose the advantages of direct calculation. BeO has been examined in two basis sets. For CH+, four different basis sets have been used. We have presented the partial fourth-order schemes to the EA in all the basis sets. The results are analyzed to illustrate the importance of triples, as well as highlight computationally efficient partial fourth-order schemes. The choice of the basis set on the electron affinity calculation is also emphasized. Comparisons with available experimental and theoretical results are presented. The general fourth-order schemes, which are conceptually equivalent with the Fock-space multi-reference coupled-cluster singles, doubles, and triplets (MRCCSD+T) methods, based on bondonic formalism, are also presented here in a composed way, for quantum electronic affinity.

scholarly journals THERMOCHEMICAL PARAMETERS OF SOME SMALL PURE AND DOPED SILICON CLUSTERS

2018 ◽  
Vol 55 (6A) ◽  
pp. 18
Author(s):  
Nguyen Minh Tam
Keyword(s):  
Quantum Chemical ◽  
Large Error ◽  
Basis Set ◽  
Coupled Cluster ◽  
Electron Affinities ◽  
Silicon Clusters ◽  
Coupled Cluster Theory ◽  
Doped Silicon ◽  
Thermochemical Parameters ◽  
Quantum Chemical Computations

Quantum chemical computations of thermochemical parameters of several series of small pure and doped silicon clusters are reviewed. We analyzed the performance of the coupled-cluster theory with energies extrapolated up to complet basis set, CCSD(T)/CBS and the composite G4 method in determining the total atomization energies (TAE), standard heats of formation (∆fH0), electron affinities (EA) and ionization energies (IE) and other thermochemical parameters with respect to available experimental data. The latter were determined with large error margins.

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