New algorithms for an individually selecting MR-CI program

Hanrath, Michael; Engels, Bernd

doi:10.1016/s0301-0104(97)00241-3

Cited by 161 publications

(100 citation statements)

References 17 publications

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“…The active space for the C 1 -symmetrical species 6 a was chosen as the three highest occupied and three lowest unoccupied molecular orbitals (MOs) of the a irreducible representation, leading to a calculations were performed with the MOLCAS program package. [25] The MR-CI approach used in this study is based on an individually selecting multireference CISD algorithm [26] to reduce the dimension of the CI eigenvalue problem. The contribution of the configurational state functions neglected in the CI procedure was taken into account by the Buenker ± Peyerimhoff extrapolation scheme.…”

Section: Resultsmentioning

confidence: 99%

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ²‐1H‐Pyridine) and Its Benzo Derivative (3δ²‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ²‐1H‐quinoline

Schöneboom

Groetsch

Christl

et al. 2003

Chemistry A European J

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Treatment of a solution of 3-bromo-1-methyl-1,2-dihydroquinoline (9) and [18]crown-6 in furan or styrene with KOtBu followed by hydrolysis afforded a mixture of 1-methyl-1,2-dihydroquinoline (10) and 1-methyl-2-quinolone (11). If the reaction was performed in [D(8)]THF and the mixture was immediately analysed by NMR spectroscopy, 2-tert-butoxy-1-methyl-1,2-dihydroquinoline (17) was shown to be the precursor of 10 and 11. The structure of 17 is evidence for the title cycloallene 7, which arises from 9 by beta elimination of hydrogen bromide and is trapped by KOtBu to give 17 so fast that cycloadditions of 7 with furan or styrene cannot compete. Since this reactivity is unusual compared to the large majority of the known six-membered cyclic allenes, we performed quantum-chemical calculations on 8, which is the parent compound of 7, and the corresponding isopyridine 6 to assess the electronic nature of these species. The ground state of 6 was no longer an allene (6 a) but the zwitterion 6 b. In the case of 8, the allene structure 8 a is more stable than the zwitterionic form 8 b by only approximately 1 kcal mol(-1). These results suggest a high reactivity of 6 and 8 towards nucleophiles and explains the behaviour of 7. In addition to the ground states, the low-lying excited states of 6 and 8 were considered, which are represented by the diradicals 6 c and 8 c and, as singlets, lie above 6 b and 8 a by 19.1-24.8 and 14.4-17.7 kcal mol(-1), respectively.

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Section: Resultsmentioning

confidence: 99%

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ²‐1H‐Pyridine) and Its Benzo Derivative (3δ²‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ²‐1H‐quinoline

Schöneboom

Groetsch

Christl

et al. 2003

Chemistry A European J

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“…II). An alternative strategy is given by so-called direct methods, 30,31,32,33,34,35,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58 where required matrix elements are computed on the fly during each step of recursive diagonalization of the many-electron Hamiltonian. The latter approach constitutes an interesting direction for future work, together with possible interfaces with other CI codes.…”

Section: Discussionmentioning

confidence: 99%

Full configuration interaction approach to the few-electron problem in artificial atoms

Rontani¹,

Cavazzoni

Bellucci

et al. 2006

The Journal of Chemical Physics

183

202

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We present a new high-performance configuration interaction code optimally designed for the calculation of the lowest energy eigenstates of a few electrons in semiconductor quantum dots (also called artificial atoms) in the strong interaction regime. The implementation relies on a singleparticle representation, but it is independent of the choice of the single-particle basis and, therefore, of the details of the device and configuration of external fields. Assuming no truncation of the Fock space of Slater determinants generated from the chosen single-particle basis, the code may tackle regimes where Coulomb interaction very effectively mixes many determinants. Typical strongly correlated systems lead to very large diagonalization problems; in our implementation, the secular equation is reduced to its minimal rank by exploiting the symmetry of the effective-mass interacting Hamiltonian, including square total spin. The resulting Hamiltonian is diagonalized via parallel implementation of the Lanczos algorithm. The code gives access to both wave functions and energies of first excited states. Excellent code scalability in a parallel environment is demonstrated; accuracy is tested for the case of up to eight electrons confined in a two-dimensional harmonic trap as the density is progressively diluted up to the Wigner regime, where correlations become dominant. Comparison with previous Quantum Monte Carlo simulations in the Wigner regime demonstrates power and flexibility of the method.

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“…In the complex SCF calculations, the variational principle is applied to obtain the eigenfunctions of the molecular orbital, which serve as one-electron basis functions for constructing the determinantal wavefunctions. In the CI calculation, all electrons are treated as active and the single-and double-excitations are included to construct the configuration space, and the individual selection schemes 39 specific for each reference configurations are applied for the configuration selections and the Davidson subspace method 55,56 is used for diagonalization. Finally, stationary solutions of the energy expectation value on the scaling parameter η can be found in the complex plane by varying α and θ.…”

Section: Theoretical Methodsmentioning

confidence: 99%

Complex multireference configuration interaction calculations for the K-vacancy Auger states of N q+ (q = 2-5) ions

Peng

Zhu

et al. 2016

The Journal of Chemical Physics

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Ab initio multireference configuration-interaction theoretical study on the low-lying spin states in binuclear transition-metal complex: Magnetic exchange of [ ( NH 3 ) K-vacancy Auger states of N q+ (q = 2-5) ions are studied by using the complex multireference single-and double-excitation configuration interaction (CMRD-CI) method. The calculated resonance parameters are in good agreement with the available experimental and theoretical data. It shows that the resonance positions and widths converge quickly with the increase of the atomic basis sets in the CMRD-CI calculations; the standard atomic basis set can be employed to describe the atomic K-vacancy Auger states well. The strong correlations between the valence and core electrons play important roles in accurately determining those resonance parameters, Rydberg electrons contribute negligibly in the calculations. Note that it is the first time that the complex scaling method has been successfully applied for the B-like nitrogen. CMRD-CI is readily extended to treat the resonance states of molecules in the near future. C 2016 AIP Publishing LLC. [http://dx

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New algorithms for an individually selecting MR-CI program

Cited by 161 publications

References 17 publications

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ²‐1H‐Pyridine) and Its Benzo Derivative (3δ²‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ²‐1H‐quinoline

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ²‐1H‐Pyridine) and Its Benzo Derivative (3δ²‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ²‐1H‐quinoline

Full configuration interaction approach to the few-electron problem in artificial atoms

Complex multireference configuration interaction calculations for the K-vacancy Auger states of N q+ (q = 2-5) ions

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New algorithms for an individually selecting MR-CI program

Cited by 161 publications

References 17 publications

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ2‐1H‐Pyridine) and Its Benzo Derivative (3δ2‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ2‐1H‐quinoline

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ2‐1H‐Pyridine) and Its Benzo Derivative (3δ2‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ2‐1H‐quinoline

Full configuration interaction approach to the few-electron problem in artificial atoms

Complex multireference configuration interaction calculations for the K-vacancy Auger states of N q+ (q = 2-5) ions

Contact Info

Product

Resources

About

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ²‐1H‐Pyridine) and Its Benzo Derivative (3δ²‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ²‐1H‐quinoline

Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ²‐1H‐Pyridine) and Its Benzo Derivative (3δ²‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ²‐1H‐quinoline