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Avogadro with Gaussian + NBO
Avogadro with Gaussian + NBO
Published: 2015/05/06
Channel: IaNiusha
Comparing an MO with the Corresponding NBO Using WebMO
Comparing an MO with the Corresponding NBO Using WebMO
Published: 2016/04/10
Channel: John Keller
03.03 Localized Molecular Orbitals and NBO Theory
03.03 Localized Molecular Orbitals and NBO Theory
Published: 2017/11/16
Channel: Michael Evans
Multiple NBOS With GaussView and WebMO
Multiple NBOS With GaussView and WebMO
Published: 2016/04/12
Channel: John Keller
03.04 NBO Analysis of Methane
03.04 NBO Analysis of Methane
Published: 2017/11/16
Channel: Michael Evans
Valence Bond Theory, Hybrid Orbitals, and Molecular Orbital Theory
Valence Bond Theory, Hybrid Orbitals, and Molecular Orbital Theory
Published: 2016/01/10
Channel: Professor Dave Explains
03.05 Shapes of Natural Bond Orbitals
03.05 Shapes of Natural Bond Orbitals
Published: 2017/11/16
Channel: Michael Evans
Jmol Viewer and display of NBOs in web browsers
Jmol Viewer and display of NBOs in web browsers
Published: 2012/11/18
Channel: Org Med Chem
Molecular Orbital Theory VI: Paramagnetism and Diamagnetism
Molecular Orbital Theory VI: Paramagnetism and Diamagnetism
Published: 2011/08/08
Channel: Ben's Chem Videos
03.06 Polarization and Relative Energies
03.06 Polarization and Relative Energies
Published: 2017/11/16
Channel: Michael Evans
5.3 Ozone [SL IB Chemistry]
5.3 Ozone [SL IB Chemistry]
Published: 2014/03/02
Channel: Richard Thornley
IboView: visualizer with style
IboView: visualizer with style
Published: 2016/02/21
Channel: IaNiusha
ADF Tutorial 11: Caffeine Bader (AIM) analysis, Benzene NBO visualization and Occupations
ADF Tutorial 11: Caffeine Bader (AIM) analysis, Benzene NBO visualization and Occupations
Published: 2015/12/10
Channel: AmsterdamDensityFunctional
Beautiful Visualization of Molecular Orbitals
Beautiful Visualization of Molecular Orbitals
Published: 2017/07/14
Channel: Rangsiman Ketkaew
Interpreting Gaussian Results
Interpreting Gaussian Results
Published: 2012/07/25
Channel: me0and0the0piano
Quantum Chemistry ; (NPA) Natural Population Analysis: JANPA with ORCA and Psi4 programs
Quantum Chemistry ; (NPA) Natural Population Analysis: JANPA with ORCA and Psi4 programs
Published: 2017/08/20
Channel: Hamza allal
Jmol-NBO Visualization Helper
Jmol-NBO Visualization Helper
Published: 2013/07/28
Channel: Org Med Chem
Jmol MOs and PowerPoint
Jmol MOs and PowerPoint
Published: 2016/02/05
Channel: John Keller
GenNbo Helper 1.0
GenNbo Helper 1.0
Published: 2013/07/26
Channel: Org Med Chem
ETS-NOCV: Advanced chemical bonding analysis
ETS-NOCV: Advanced chemical bonding analysis
Published: 2014/03/03
Channel: AmsterdamDensityFunctional
Intrinsic Bond Orbital Analysis of a Strain-Promoted Alkyne Azide Cycloaddition
Intrinsic Bond Orbital Analysis of a Strain-Promoted Alkyne Azide Cycloaddition
Published: 2017/02/17
Channel: Click Chemist
Create Jmol Scripts for NBO Visualization
Create Jmol Scripts for NBO Visualization
Published: 2013/02/18
Channel: Org Med Chem
Molecular Orbitals of Ethene
Molecular Orbitals of Ethene
Published: 2012/10/30
Channel: Jay Shore
NBO Income Calculator
NBO Income Calculator
Published: 2014/03/30
Channel: Uling Cyril
NBO visualizer FAIL
NBO visualizer FAIL
Published: 2015/10/25
Channel: IaNiusha
Mulliken population analysis Top # 6 Facts
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Published: 2015/10/30
Channel: Himandri Sinha
KNIME UGM 2013 Bernd Wiswedel talk- Part 3 NBO
KNIME UGM 2013 Bernd Wiswedel talk- Part 3 NBO
Published: 2013/03/22
Channel: KNIMETV
NBO analysis-organicchemistry Wagner College
NBO analysis-organicchemistry Wagner College
Published: 2014/11/19
Channel: Rob Craig
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Time evolution of the density, natural orbitals, and Sg
Published: 2014/09/23
Channel: Quantum Cinema
Avogadro with Gaussian Tutorial Electron Density
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Channel: IaNiusha
Orbital Calculation
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Published: 2014/01/11
Channel: ahmad fitri
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03.01 The Orbital Concept
Published: 2017/11/14
Channel: Michael Evans
Avogadro with Gaussian Tutorial MOs
Avogadro with Gaussian Tutorial MOs
Published: 2012/06/01
Channel: IaNiusha
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Gaussian Frequency Analysis
Published: 2013/10/30
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Nbo Fast track system English version
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Published: 2014/04/10
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Published: 2014/12/29
Channel: viascience
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Hybridization of Orbitals
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Polymers - Crash Course Chemistry #45
Published: 2014/01/06
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Published: 2015/04/18
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Calculating the energy for the singlet and triplet states of a carbon atom
Published: 2014/02/07
Channel: PChem CWU
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Published: 2011/10/16
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iGCSE / GCSE Chemistry: What are Bond energies?
Published: 2015/10/23
Channel: IGCSE World
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The Ideal Gas Law: Crash Course Chemistry #12
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WIKIPEDIA ARTICLE

From Wikipedia, the free encyclopedia
  (Redirected from Natural Bond Orbital)
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In quantum chemistry, a natural bond orbital or NBO is a calculated bonding orbital with maximum electron density. The NBOs are one of a sequence of natural localized orbital sets that include "natural atomic orbitals" (NAO), "natural hybrid orbitals" (NHO), "natural bonding orbitals" (NBO) and "natural (semi-)localized molecular orbitals" (NLMO). These natural localized sets are intermediate between basis atomic orbitals (AO) and molecular orbitals (MO):

Atomic orbital → NAO → NHO → NBO → NLMO → Molecular orbital

Natural (localized) orbitals are used in computational chemistry to calculate the distribution of electron density in atoms and in bonds between atoms. They have the "maximum-occupancy character" in localized 1-center and 2-center regions of the molecule. Natural bond orbitals (NBOs) include the highest possible percentage of the electron density, ideally close to 2.000, providing the most accurate possible “natural Lewis structure” of ψ. A high percentage of electron density (denoted %-ρL), often found to be >99% for common organic molecules, correspond with an accurate natural Lewis structure.

The concept of natural orbitals was first introduced by Per-Olov Löwdin in 1955, to describe the unique set of orthonormal 1-electron functions that are intrinsic to the N-electron wavefunction.[1]

Theory[edit]

Each bonding NBO σAB (the donor) can be written in terms of two directed valence hybrids (NHOs) hA, hB on atoms A and B, with corresponding polarization coefficients cA, cB:

σAB = cA hΑ + cB hB

The bonds vary smoothly from covalent (cA = cB) to ionic (cA >> cB) limit.

Each valence bonding NBO σ must be paired with a corresponding valence antibonding NBO σ* (the acceptor) to complete the span of the valence space:

σAB* = cA hΑcB hB

The bonding NBOs are of the "Lewis orbital"-type (occupation numbers near 2); antibonding NBOs are of the "non-Lewis orbital"-type (occupation numbers near 0). In an idealized Lewis structure, full Lewis orbitals (two electrons) are complemented by formally empty non-Lewis orbitals. Weak occupancies of the valence antibonds signal irreducible departures from an idealized localized Lewis structure, which means true "delocalization effects".[1]

Lewis structures[edit]

With a computer program that can calculate NBOs, optimal Lewis structures can be found. An optimal Lewis structure can be defined as that one with the maximum amount of electronic charge in Lewis orbitals (Lewis charge). A low amount of electronic charge in Lewis orbitals indicates strong effects of electron delocalization.

In resonance structures, major and minor contributing structures may exist. For amides, for example, NBO calculations show that the structure with a carbonyl double bond is the dominant Lewis structure. However, in NBO calculations, "covalent-ionic resonance" is not needed due to the inclusion of bond-polarity effects in the resonance structures.[2] This is similar to other modern valence bond theory methods.

See also[edit]

References[edit]

  1. ^ a b Weinhold, Frank; Landis, Clark R. (2001). "Natural Bond Orbitals and Extensions of Localized Bonding Concepts" (PDF). Chemistry Education Research and Practice. 2 (2): 91–104. doi:10.1039/B1RP90011K. 
  2. ^ Weinhold, Frank; Landis, Clark R. (2012). Discovering Chemistry With Natural Bond Orbitals. New Jersey: John Wiley & Sons. pp. 132–133. ISBN 978-1-118-22916-3. 

External links[edit]

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