Ability of the CNDO/2 and INDO MO methods to cope with nonbonded interactions

Gregory, Allan R.; Paddon‐Row, Michael N.

doi:10.1021/ja00440a011

Cited by 50 publications

(14 citation statements)

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“…This is in accordance with previous findings that the ZPVE has only a small effect on the energy barrier. [43] Importantly, the barrier height for the 1 Ǟ 2 interconversion taking 1 as the reactant is 22.7 kcal mol -1 if ZPVE is included, which is in excellent agreement with the value of 22 kcal mol -1 measured by Eaton and Temme. [17] [16] CASSCF(2,2) 5.1 20.5 [15,16] MP2/CASSCF(2,2) 5.7 21.6 [16] MP2/CASSCF(2,2)+ZPVE 4.8 19.8 [16] CASSCF(4,4) 5.2 21.3 0.6 -56.9 [16] MP2/CASSCF(4,4) 8.4 25.2 [16] CASSCF (8,8) 6.9 24.1 0.3 [16] MP2/CASSCF (8,8) 15.1 33.5 [16] MP2/CASSCF(8,8)+ZPVE 14.9 33.4 [16] B3LYP (unrs, unpr) 3.9 28.7 -47.1 [16] BLYP (REKS) ≈10 ≈36 [47] [a] The total electronic and ZPVE energies for our best calculation of the reference point 2 are -310.91434 and 0.18178 a.u., respectively.…”

Section: Resultssupporting

confidence: 84%

[2.2.2]Propellane Isomerization by Grob Rearrangement: An Ab Initio MR‐AQCC Study

et al. 2007

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The multireference average quadratic couple cluster (MR-AQCC) method has been employed to explore isomerism in the [2.2.2]propellane 1 as well as the accompanying Grobtype fragmentation. It is shown that the open form 2 is more stable than the conventional closed propellane 1 by 3.6 kcal mol -1 . These two isomers are separated by a barrier as high as 22.7 kcal mol -1 , taking 1 as a reactant, a value that is in excellent agreement with experiment. However, system 2 is not a stable species because it is located in a very shallow energy minimum. Consequently, it undergoes almost barrierless cage-opening to the thermodynamically most stable

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Section: Resultssupporting

confidence: 84%

[2.2.2]Propellane Isomerization by Grob Rearrangement: An Ab Initio MR‐AQCC Study

et al. 2007

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“…Comparison of these data with those calculated by MR-AQCC method [9] reveals that relative stability of diradical 1b with respect to 1a is more pronounced and that the energy barrier for interconversion between structures 1a and 1b is underestimated by 8 kcal mol -1 . As previously found at MR-AQCC level, [9,30] the ZPVE correction to the energy barrier at CASSCF level is small. Refinement of the energy of the CASSCF optimized stationary points using CASPT2 method reduces the relative stability of structure 1b to 3.2 kcal mol -1 what is in …”

Section: Validation Of the Computational Methodssupporting

confidence: 78%

The Influence of Multiple Fluorination on the Ring Opening of [2.2.2]Propellane

Antol¹,

Eckert‐Maksić²

2017

Croat. Chem. Acta

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Effect of electronegative substituents on ring opening of [2.2.2]propellane was examined by quantum chemical calculations at CASSCF and CASPT2 level of theory. Comparison of the results with those obtained with MR-AQCC calculations indicated that calculations beyond CASSCF level were needed for reliable description of the process. Calculations show a strong effect of fluorination on the central bond elongation energy profile, with the effect being most pronounced for the perfluoro derivative. Moreover, for rearrangement of the most of multiply fluorinated derivatives, including perfluoro[2.2.2]propellane, CASPT2 calculations predict a single minimum potential energy well, which hampers rearrangement to significantly more stable fluorinated 1,4-dimethylenecyclohexane analogues. This observation is in harmony with high stability of synthetically available stable heavily fluorinated derivatives which, in contrast to the parent [2.2.2]propellane, do not rearrange to the thermodynamically most stable fluorinated 1,4-dimethylene-cyclohexane isomer.

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“…3 and 4) practically no stabilization can be observed [14,15,26]. However, the C N D O /~ method predicts the stable 0-0 water dimer [13,141, as well as the ethylene dimer [15]. In the former case the supermolecule CND0/2 (INDO) method gives Re, = 1.60 8,…”

Section: B Systems With Repulsive Potentialsmentioning

confidence: 98%

“…Thus, especially in the prediction of interaction energies and geometries of charge-transfer complexes, the results are completely erroneous [8-121 (i.e., interaction energies are too large and the intermolecular distances too short). Moreover, the recently published results of calculations for the water dimer [13,14] as well as those of ethylene dimer [15] lead to artificial geometries and not to correct stabilization energies.…”

Section: Introductionmentioning

confidence: 99%

Ghost orbitals in semiempirical methods. Estimation of basis set superposition error

Lipiński¹,

Chojnacki²

1981

Int J of Quantum Chemistry

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Based on the all-valence ZDO SCF approximation a procedure for estimating the basis set superposition error (BSSE) in semiempirical C N D~/ I N D O methods has been proposed. The results of the calculation show that the BSSE effect may improve the results obtained from the standard CNDOIINDO supermolecule calculation. The estimated BSSE effect enables one to explain some recently reported artificial structures for water and ethylene dimers.

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Ability of the CNDO/2 and INDO MO methods to cope with nonbonded interactions

Cited by 50 publications

References 0 publications

[2.2.2]Propellane Isomerization by Grob Rearrangement: An Ab Initio MR‐AQCC Study

[2.2.2]Propellane Isomerization by Grob Rearrangement: An Ab Initio MR‐AQCC Study

The Influence of Multiple Fluorination on the Ring Opening of [2.2.2]Propellane

Ghost orbitals in semiempirical methods. Estimation of basis set superposition error

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