Mass Spectrometry of Cyclopentadienylideneketene: Differentiation of Isomeric Ion Structures by Means of Ion/Molecule Reactions

2012 ◽  
Vol 65 (12) ◽  
pp. 1655 ◽  
Author(s):  
Pascal Gerbaux ◽  
Curt Wentrup
Keyword(s):  
Mass Spectrometry ◽  
Density Functional Theory ◽  
Density Functional ◽  
Large Scale ◽  
Density Functional Theory Calculations ◽  
Molecular Ions ◽  
Functional Theory ◽  
Clear Cut ◽  
Ion Molecule Reactions ◽  
Hybrid Mass Spectrometer

The nature of the m/z 104 ions formed by loss of CO2 or Ph-O-NCO from the molecular ions of phthalic anhydride, N-phenoxyphthalimide, and N-phenoxyisophthalimide was investigated by means of ion/molecule reactions with acetone. This allows a clear-cut differentiation of the so-obtained ions from the isomeric molecular ions of cyclopentadienylideneketene. The different intrinsic chemical reactivities of ionized cyclopentadienylideneketene and its distonoid isomer towards neutral acetone were investigated on a large-scale hybrid mass spectrometer and confirmed by density functional theory calculations.

scholarly journals Tensor-structured algorithm for reduced-order scaling large-scale Kohn–Sham density functional theory calculations

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Chih-Chuen Lin ◽  
Phani Motamarri ◽  
Vikram Gavini
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Large Scale ◽  
Density Functional Theory Calculations ◽  
System Size ◽  
Real Space ◽  
Functional Theory ◽  
Reduced Order ◽  
Separable Approximation ◽  
Tensor Basis

AbstractWe present a tensor-structured algorithm for efficient large-scale density functional theory (DFT) calculations by constructing a Tucker tensor basis that is adapted to the Kohn–Sham Hamiltonian and localized in real-space. The proposed approach uses an additive separable approximation to the Kohn–Sham Hamiltonian and an L1 localization technique to generate the 1-D localized functions that constitute the Tucker tensor basis. Numerical results show that the resulting Tucker tensor basis exhibits exponential convergence in the ground-state energy with increasing Tucker rank. Further, the proposed tensor-structured algorithm demonstrated sub-quadratic scaling with system-size for both systems with and without a gap, and involving many thousands of atoms. This reduced-order scaling has also resulted in the proposed approach outperforming plane-wave DFT implementation for systems beyond 2000 electrons.

Nb2BN2− cluster anions reduce four carbon dioxide molecules: reactivity enhancement by ligands

2020 ◽  
Vol 49 (40) ◽  
pp. 14081-14087 ◽  
Author(s):  
Hai-Yan Zhou ◽  
Ming Wang ◽  
Yong-Qi Ding ◽  
Jia-Bi Ma
Keyword(s):  
Mass Spectrometry ◽  
Carbon Dioxide ◽  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Cluster Anions ◽  
Gas Phase Reactions ◽  
Functional Theory ◽  
Flight Mass Spectrometry

The thermal gas-phase reactions of Nb2BN2− cluster anions with carbon dioxide have been explored by using the art of time-of-flight mass spectrometry and density functional theory calculations.

scholarly journals Mechanism of the Oxidation of Heptafulvenes to Tropones Studied by Online Mass Spectrometry and Density Functional Theory Calculations

2019 ◽  
Vol 84 (21) ◽  
pp. 13975-13982
Author(s):  
Sofia M. E. Nilsson ◽  
Henning Henschel ◽  
Gianmario Scotti ◽  
Markus Haapala ◽  
Alexandros Kiriazis ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory

An octacoordinated Nb atom in the NbAl8H8+ cluster

2021 ◽  
Author(s):  
Piero Ferrari ◽  
Hung Tan Pham ◽  
Jan Vanbuel ◽  
Andre Fielicke ◽  
Minh T. Nguyen ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Density Functional Theory ◽  
Infrared Spectroscopy ◽  
Density Functional ◽  
Molecular Beam ◽  
Density Functional Theory Calculations ◽  
High Symmetry ◽  
Functional Theory

The NbAl8H8+ cluster was formed in a molecular beam and characterized by mass spectrometry and infrared spectroscopy. Density functional theory calculations showed that its lowest-energy isomer is a high symmetry...

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