A MNDO study of carbon clusters with specifically fitted parameters

Tseng, Shiuh-ping; Shen, Min-yi; Yu, Chin‐Hui

doi:10.1007/bf01113867

Cited by 19 publications

(5 citation statements)

References 60 publications

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“…These calculations were already shown to be successful in predicting the overall absorption pattern and the vibrational frequencies, as well as the molecular structures of the basic fullerenes C 60 and C 70 [31][32][33][34][35]. Excellent agreement with the experimental data was observed [23,24,[36][37][38].…”

Section: Introductionmentioning

confidence: 71%

Recent Advances in IR and UV/VIS Spectroscopic Characterization of the C₇₆ and C₈₄ Isomers of D₂ Symmetry

Jovanovic

Koruga

Jovančićević

2014

Journal of Nanomaterials

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The stable isomers of the higher fullerenes C 76 and C 84 with D 2 symmetry as well as the basic fullerenes C 60 and C 70 were isolated from carbon soot and characterized by the new and advanced methods, techniques, and processes. The validity of several semiempirical, ab initio, and DFT theoretical calculations in predicting the general pattern of IR absorption and the vibrational frequencies, as well as the molecular electronic structure of the C 76 and C 84 isomers of D 2 symmetry, is confirmed, based on recent experimental results. An excellent correlation was found between the previously reported theoretical data and the recently obtained experimental results for these molecules over the relevant spectral range for the identification of fullerenes. These results indicate that there are no errors in the calculations in the significant spectral regions, the assumptions that were based on previous comparisons with partial experimental results. Isolated fullerenes are important for their applications in electronic and optical devices, solar cells, optical limiting, sensors, polymers, nanophotonic materials, diagnostic and therapeutic agents, health and environment protection, and so forth.

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Section: Introductionmentioning

confidence: 71%

Recent Advances in IR and UV/VIS Spectroscopic Characterization of the C₇₆ and C₈₄ Isomers of D₂ Symmetry

Jovanovic

Koruga

Jovančićević

2014

Journal of Nanomaterials

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“…SQC parameters are sometimes refitted specifically for some class of compounds (e.g., fullerenes 13 ), for certain reactions (e.g., to study kinetic isotopic effects 14 ) or for intermolecular interactions (e.g., in water 15 ). The resulting special-purpose SQC approaches can achieve high accuracy by closely reproducing experimental or high-level QC data for the target systems.…”

Section: Introductionmentioning

confidence: 99%

“…9,10 While this general-purpose strategy often provides acceptable average accuracy in a statistical sense, 9,10 SQC calculations may be quite inaccurate for particular compounds. 11,12 SQC parameters are sometimes refitted specifically for some class of compounds (e.g., fullerenes 13 ), for certain reactions (e.g., to study kinetic isotopic effects 14 ) or for intermolecular interactions (e.g., in water 15 ). The resulting special-purpose SQC approaches can achieve high accuracy by closely reproducing experimental or high-level QC data for the target systems.…”

Section: Introductionmentioning

confidence: 99%

Machine Learning of Parameters for Accurate Semiempirical Quantum Chemical Calculations

Dral

Lilienfeld

Thiel

2015

J. Chem. Theory Comput.

105

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We investigate possible improvements in the accuracy of semiempirical quantum chemistry (SQC) methods through the use of machine learning (ML) models for the parameters. For a given class of compounds, ML techniques require sufficiently large training sets to develop ML models that can be used for adapting SQC parameters to reflect changes in molecular composition and geometry. The ML-SQC approach allows the automatic tuning of SQC parameters for individual molecules, thereby improving the accuracy without deteriorating transferability to molecules with molecular descriptors very different from those in the training set. The performance of this approach is demonstrated for the semiempirical OM2 method using a set of 6095 constitutional isomers C7H10O2, for which accurate ab initio atomization enthalpies are available. The ML-OM2 results show improved average accuracy and a much reduced error range compared with those of standard OM2 results, with mean absolute errors in atomization enthalpies dropping from 6.3 to 1.7 kcal/mol. They are also found to be superior to the results from specific OM2 reparameterizations (rOM2) for the same set of isomers. The ML-SQC approach thus holds promise for fast and reasonably accurate high-throughput screening of materials and molecules.

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“…A specific parametrization − is usually expected to deteriorate performance for general-purpose applications, and thus, we adopted the above 5 subsets of the GMTKN30-HCNO database as subset III, in an attempt to maintain the applicability to energetics of chemical reactions. Several subsets such as W4-08, G21IP (adiabatic ionization potentials), SIE11 (self-interaction error related problems), and RSE43 (radical stabilization energies) involve open-shell doublets and/or triplets.…”

Section: Computational Detailsmentioning

confidence: 99%

Reparameterization of PM6 Applied to Organic Diradical Molecules

2016

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We have performed a reparameterization of PM6 (called rPM6) to compute open-shell species, specifically organic diradical molecules, within a framework of the spin-unrestricted semiempirical molecular orbital (SE-UMO) method. The parameters for the basic elements (hydrogen, carbon, nitrogen, and oxygen) have been optimized simultaneously using the training set consisting of 740 reference data. On the basis of the GMTKN30 database, the mean absolute error of rPM6 is decreased from 16.1 to 14.1 kcal/mol, which reassures its accuracy for ground-state properties. Applications of the spin-unrestricted rPM6 (UrPM6) method to small diradicals and relatively large polycyclic aromatic hydrocarbons have provided substantial improvement over the standard SE-UMO methods like UAM1, UPM3, and the original UPM6. The UrPM6 calculation is much less susceptible to spin contamination and, therefore, reproduces geometric parameters and adiabatic singlet-triplet energy gaps obtained by UDFT (UB3LYP and/or UBHandHLYP) at much lower computational cost.

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A MNDO study of carbon clusters with specifically fitted parameters

Cited by 19 publications

References 60 publications

Recent Advances in IR and UV/VIS Spectroscopic Characterization of the C₇₆ and C₈₄ Isomers of D₂ Symmetry

Recent Advances in IR and UV/VIS Spectroscopic Characterization of the C₇₆ and C₈₄ Isomers of D₂ Symmetry

Machine Learning of Parameters for Accurate Semiempirical Quantum Chemical Calculations

Reparameterization of PM6 Applied to Organic Diradical Molecules

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A MNDO study of carbon clusters with specifically fitted parameters

Cited by 19 publications

References 60 publications

Recent Advances in IR and UV/VIS Spectroscopic Characterization of the C76 and C84 Isomers of D2 Symmetry

Recent Advances in IR and UV/VIS Spectroscopic Characterization of the C76 and C84 Isomers of D2 Symmetry

Machine Learning of Parameters for Accurate Semiempirical Quantum Chemical Calculations

Reparameterization of PM6 Applied to Organic Diradical Molecules

Contact Info

Product

Resources

About

Recent Advances in IR and UV/VIS Spectroscopic Characterization of the C₇₆ and C₈₄ Isomers of D₂ Symmetry

Recent Advances in IR and UV/VIS Spectroscopic Characterization of the C₇₆ and C₈₄ Isomers of D₂ Symmetry