scholarly journals Real space bond orders are energetic descriptors

2018 ◽  
Vol 20 (23) ◽  
pp. 16231-16237 ◽  
Author(s):  
A. Martín Pendás ◽  
E. Francisco
Keyword(s):  
Bond Order ◽  
Real Space ◽  
Bond Orders ◽  
Chemical Interactions ◽  
Position Space

Orbital invariant position space techniques are used to show a theoretical link between the conventional concept of bond order and the energetics of chemical interactions.

scholarly journals Revitalizing the concept of bond order through delocalization measures in real space

2018 ◽  
Vol 9 (25) ◽  
pp. 5517-5529 ◽  
Author(s):  
Carlos Outeiral ◽  
Mark A. Vincent ◽  
Ángel Martín Pendás ◽  
Paul L. A. Popelier
Keyword(s):  
Bond Order ◽  
Real Space ◽  
Quantum Mechanical ◽  
Bond Orders ◽  
Exchange Correlation ◽  
Mechanical Bond ◽  
Topological Atoms

Quantum mechanical bond orders are obtained from integration of the exchange–correlation density between topological atoms.

On the π-Electron Content of Bonds and Rings in Benzenoid Hydrocarbons

2004 ◽  
Vol 59 (4-5) ◽  
pp. 295-298 ◽  
Author(s):  
Ivan Gutman ◽  
Tetsuo Morikawa ◽  
Susumu Narita
Keyword(s):  
Bond Order ◽  
Membered Ring ◽  
Electron Content ◽  
Bond Orders ◽  
Double Bonds ◽  
Benzenoid Hydrocarbons ◽  
Carbon Bond ◽  
Carbon Carbon Bond ◽  
Carbon Carbon Bonds ◽  
Single Bonds

The Pauling bond order can be viewed as a measure of the π-electron content of the respective carbon-carbon bond. In benzenoid hydrocarbons its values lie between 0 (in the case of essential single bonds) and 1 (in the case of essential double bonds). If the benzenoid molecule does not possess essential single and double bonds, then the Pauling bond orders are greater than 0 and less than 1, but may assume values arbitrarily close to 0 and 1. The π-electron content of a ring is equal to the sum of the π-electron contents of the carbon-carbon bonds forming this ring. We show that in benzenoid hydrocarbons the π-electron content of any (six-membered) ring lies between 0 and 5.5. If the molecule does not possess essential single and double bonds, then the π-electron content of any ring is greater than 0 and less than 5.5, but may assume values arbitrarily close to 0 and 5.5.

Bond order-bond length relationships in conjugated hydrocarbons - the microwave spectrum and structure of 3,4-dimethylenecyclobutene

1983 ◽  
Vol 36 (4) ◽  
pp. 639 ◽  
Author(s):  
RD Brown ◽  
PD Godfry ◽  
BT Hart ◽  
AL Ottrey ◽  
M Onda ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Ab Initio ◽  
Bond Length ◽  
Bond Order ◽  
Microwave Spectrum ◽  
Basis Set ◽  
Molecular Orbital Calculations ◽  
Bond Orders ◽  
Bond Lengths ◽  
Typical Error

The microwave spectrum of the benzene isomer 3,4-dimethylenecyclobutene including spectra of all possible single 13C-substituted and sufficient singly and doubly D-substituted species to give a complete r5 geometry, have been measured and analysed. An estimate of the re geometry has also been derived. The additional precise CC bond lengths obtained for an unsubstituted, conjugated hydrocarbon enable us to examine bond order-bond length relationships more thoroughly than has previously been possible. The CC bond lengths exhibit a noticeably better correlation with SCFMO bond orders than with simple H�ckel bond orders. Further confirmatory measurements of the dipole moment of dimethylenecyclobutene have been made. Ab initio molecular orbital calculations using a 6-31G basis set give an optimized geometry with CC bond lengths within 2 pm of the r5 values. The computed dipole moment agrees almost exactly with experiment but a corresponding calculation on fulvene is discrepant with experiment by 0.16 D, which is probably a more typical error.

Bond-Order Potentials for Molybdenum and Niobium: An Assessment of Their Quality

1998 ◽  
Vol 538 ◽  
Author(s):  
M. Mrovec ◽  
V. Vitek ◽  
D. Nguyen-Manh ◽  
D. G. Pettifor ◽  
L. G. Wang ◽  
...  
Keyword(s):  
Bond Order ◽  
Tight Binding ◽  
Direct Calculation ◽  
Real Space ◽  
Central Force ◽  
Full Potential ◽  
Extended Defects ◽  
Many Body ◽  
Deformation Path ◽  
Bond Order Potentials

AbstractThe bond-order potentials (BOP) have been constructed for Mo and Nb. These potentials are based on the real-space parametrized tight-binding method in which diagonalization of the Hamiltonian is avoided by direct calculation of the bond-order. In this scheme the energy consists of three parts: The bond part that comprises contributions of d electrons and introduces into the scheme the covalent character of bonding, the central-force many-body part that reflects the environmental dependence of sp overlap repulsion and a pair-wise contribution. The potentials were tested by calculation of energy differences between the bcc and several alternate structures and by investigating the trigonal deformation path. These calculations have been made in parallel using BOP and the full-potential linearized augmented plane-wave method. The central-force many-body Finnis-Sinclair type potentials have also been included into the study of the deformation path. This evaluation of BOP reveals that the potentials reproduce very closely the ab initio results and are, therefore, very suitable for atomistic studies of extended defects in the transition metals.

scholarly journals Revitalizing the Concept of Bond Order Through Delocalization Measures in Real Space

2018 ◽  
Author(s):  
Carlos Outeiral Rubiera ◽  
Mark Vincent ◽  
Ángel Martín Pendás ◽  
Paul L. A. Popelier
Keyword(s):  
Ab Initio ◽  
Quantum Chemical ◽  
Bond Order ◽  
Large Body ◽  
Real Space ◽  
Chemical Topology ◽  
Delocalization Index ◽  
Consistent Manner ◽  
Quantum Chemical Topology ◽  
Source Of Information

Ab initio quantum chemistry is an independent source of information supplying an ever widening group of experimental chemists. However, bridging the gap between these ab initio data and chemical insight remains a challenge. In particular, there is a need for a bond order index that characterizes novel bonding patterns in a reliable manner, while recovering the familiar effects occurring in well-known bonds. In this article, through a large body of calculations, we show how the delocalization index derived from Quantum Chemical Topology (QCT) serves as such a bond order. This index is defined in a parameter-free, intuitive and consistent manner, and with little qualitative dependency on the level of theory used. The delocalization index is also able to detect the subtler bonding effects that underpin most practical organic and inorganic chemistry. We explore and connect the properties of this index and open the door for its extensive usage in the understanding and discovery of novel chemistry.

scholarly journals Atomic Charges, Surface Electrostatic Potential Analysis, and Bond Order Analysis on Nitriles and Isocyanides

2021 ◽  
Author(s):  
Yanyun Zhao ◽  
Xueli Cheng
Keyword(s):  
Electrostatic Potential ◽  
Bond Order ◽  
Atomic Charges ◽  
Bond Orders ◽  
Potential Analysis ◽  
Order Analysis ◽  
Population Analyses ◽  
Full Optimization ◽  
Global And Local ◽  
Surface Electrostatic Potential

Abstract Isocyanide-nitrile rearrangement has long been a continuing and interesting topic. A series of nitriles and isocyanides with the substituents of R=-AlH2, -BeH, -BH2, -C ≡ CH, -CF3, -CH3, -Cl, -C ≡ N, -COOH, -F, -H, Li, -MgH, -Na, -NH2, -NO2, -OH, -PH2, -SH, -SiH3, -CH = CH2 were investigated systematically based on full optimization at B3LYP-D3(BJ)/def2-QZVP level, and the isomerization energies from R-C ≡ N to :C = N-R were estimated. The substituent effect and bonding characters were analyzed by surface ESP colored van der Waals surfaces in conjunction with the global and local electrostatic extrema, the population analyses in terms of Hirshfeld and ADCH atomic charges, and bond order analyses via Laplacian and fuzzy bond orders.

scholarly journals Revitalizing the Concept of Bond Order Through Delocalization Measures in Real Space

2018 ◽  
Author(s):  
Carlos Outeiral Rubiera ◽  
Mark Vincent ◽  
Ángel Martín Pendás ◽  
Paul L. A. Popelier
Keyword(s):  
Ab Initio ◽  
Quantum Chemical ◽  
Bond Order ◽  
Large Body ◽  
Real Space ◽  
Chemical Topology ◽  
Delocalization Index ◽  
Consistent Manner ◽  
Quantum Chemical Topology ◽  
Source Of Information

Ab initio quantum chemistry is an independent source of information supplying an ever widening group of experimental chemists. However, bridging the gap between these ab initio data and chemical insight remains a challenge. In particular, there is a need for a bond order index that characterizes novel bonding patterns in a reliable manner, while recovering the familiar effects occurring in well-known bonds. In this article, through a large body of calculations, we show how the delocalization index derived from Quantum Chemical Topology (QCT) serves as such a bond order. This index is defined in a parameter-free, intuitive and consistent manner, and with little qualitative dependency on the level of theory used. The delocalization index is also able to detect the subtler bonding effects that underpin most practical organic and inorganic chemistry. We explore and connect the properties of this index and open the door for its extensive usage in the understanding and discovery of novel chemistry.

scholarly journals Bond Order Densities in Real Space

2019 ◽  
Vol 124 (2) ◽  
pp. 339-352
Author(s):  
José Luis Casals-Sainz ◽  
A. Fernández-Alarcón ◽  
Evelio Francisco ◽  
Aurora Costales ◽  
Ángel Martín Pendás
Keyword(s):  
Bond Order ◽  
Real Space
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