Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Orbital calculations

Hartree-Fock orbital Relatively accurately calculated orbital shapes. [Pg.200]

The excess energies can be measured for a known by essentially a stopping potential method, giving a spechum. This spectrum is then matched with calculated orbital energies (eigenvalues) derived from molecular orbital calculations. [Pg.323]

An extended Huckel calculation is a simple means for modeling the valence orbitals based on the orbital overlaps and experimental electron affinities and ionization potentials. In some of the physics literature, this is referred to as a tight binding calculation. Orbital overlaps can be obtained from a simplified single STO representation based on the atomic radius. The advantage of extended Huckel calculations over Huckel calculations is that they model all the valence orbitals. [Pg.33]

For the method for calculating these and similar results given in this chapter, see Higasi, K. Baba, H. Rembaum, A. Quantum Organic Chemistry Interscience NY, 1965. For values of calculated orbital energies and bond orders for many conjugated molecules, see Couison, C.A. Streitwieser Jr., A. Dictionary ofn Electron Calculations W.H. Freeman San Francisco, 1965. [Pg.79]

The regioselectivity observed was in agreement with the calculated orbital coefficients for the HOMO of heptafulvene 534 and the LUMOs of the polyenophiles. The largest coefficient in the HOMO of 534 is at C(8). The reactions of nitroethene and (E)-fi-nitrostyrene with 533 (entries 4 and 5) afforded merely exo adducts, the two isomers arising from attack of the polyenophile at the two different sites of 534. [Pg.452]

For purposes of comparison with the other calculations, the set of calculated orbital mean excitation energies shown in Table 1 were grouped in shell-hke contributions as suggested by Chen et al. [62], i.e.. [Pg.348]

The choice of active orbitals is crucial in our calculations. Orbital energies are not the most important factor when choosing the active space, but rather their shape and character. [Pg.79]

The most optimistic response to this situation is to claim that the force constant — t-bond order relationship is still valid, but that the reference points need to be changed V(CO)e itself is then a possible reference compound (76). The relationship can then only be quantified by using calculated orbital populations for the reference species, and can only be tested by more extended comparisons between calculated bond order and observed force constant. Precisely this test has been apphed to a whole group of substituted and unsubstituted octahedral carbonyls of groups VI and VII, the substituents in every case being hahde (77). The data used in fact were not force constants, but Cotton-Krainhanzel parameters this does not actually matter, since no reference molecules were used at all. Excellent agreement was found with an expression. [Pg.28]

The radical (4) appears to be a weakly associated dimer in the solid state according to CNDO-2 calculations. Orbitals of the two molecules interact forming common bonding and antibonding orbitals, hence the dimer is classified as a two-center, two-electron, h -k system (25). Thermodynamically the dimer (25) is more stable than the alternative structures in which the monomers are connected by a or N—N -bond. The dimerization energy for (25) seems to be not more... [Pg.435]

To estimate quantities such as bond energies, ionization potentials, and spectral energies of organometallic molecules, it is necessary to go further than the above qualitative approach and to calculate orbital energies. On... [Pg.16]

CHCN Fig. 8. Calculated orbital coefficients and preferred geom-... [Pg.96]

Compound Measured ionization potential (eV) Calculated orbital energy (HMO) (eV) Ref. [Pg.1046]

The fact that the neglect of the 4p orbitals in the Cr(V and Mn(V cases lead to no qualitative change hi the calculated orbital energies has led us to neglect also the id orbital in the CIO4- calculation. For this case the 3p—id separation is certainly greater than the id—4/> separation in MnCh- and Cr(V. ... [Pg.263]

We restrict our attention in this chapter to the simple but widely used Hiickel MO (HMO) method for calculating orbitals for rc-electron and aromatic molecules [2], The HMO scheme assumes that a conjugated n-electron molecule consists of a network of sp2-hybridized carbon atoms lying in a plane and each participating atom i has a 2p electron in an atomic orbital, < ) , perpendicular to this plane. Linear combinations of these atomic orbitals (LCAO) result in the molecular n wavefunctions, q/j, each of which has a discrete energy, Ej. In terms of the parameters used in HMO computations,... [Pg.903]

This chapter represents an update to the previous two editions, published in 19771 and 19892, and covers the literature of the period 1989-1994 with some references to 1995 papers. It deals mainly with electrophilic additions across the C=C, C=Si and Si=Si bonds and includes both theoretical (ab initio calculations, orbital approach, molecular modelling etc.) and experimental aspects. Particular attention is paid to mechanistic studies, facial selectivity and neighbouring group participation. Synthetic utilization of electrophilic addition is discussed only if including substantial mechanistic insight purely synthetic work is not covered. Aside from the classical reactions, such as hydration, bromination etc., newly included material comprises aziridination (Section VI), attack at C=C bond by an electron-deficient carbon (Section VII) and those electrophilic reactions which utilize a transition or non-transition metal as the electrophile (Section VIII). [Pg.1136]

The calculated molecular orbital (MO) energies are compared to those available from photoelectron spectra. The first four MOs of thiepine 1 are calculated to lie at 8.19, 10.08, 10.32, and 11.64 eV (7t 4, ji 3, n"2, and ng, respectively). The basic distribution of these orbitals is in good agreement with the photoelectron spectra of several substituted thiepines. For example, a linear relationship (slope = 1.36, intercept —2.33, R2 = 0.988) can be obtained by plotting the experimental ionization energies for 2,7-di- vt-butylthiepine 11 versus the calculated orbital energies for thiepine 1 <85JA6874>. [Pg.99]

UPS and MO theory are inextricably linked. It is impossible to interpret UPS measurements without at least a qualitative MO treatment, and it is now commonplace to perform quantitative calculations for comparison with the UPS data. The development of UPS techniques since about 1960 helped to popularise MO theory, and semi-empirical MO methods are often calibrated by appeal to UPS data. Thus an approximation which greatly simplifies an MO calculation is held to be justifiable if, over a fair range of molecules, the calculated orbital energies are in good agreement with UPS binding energies. [Pg.66]

The former ionizations are much better understood, and can now be measured experimentally by the recently developed technique of photoelectron spectroscopy 41>. A comparison between the experimental ionization potentials and the calculated orbital energies can then be made. [Pg.48]

Table 6. Comparisons of experimental ionization potentials with calculated orbital energies of alkanes and cycloalkanes... Table 6. Comparisons of experimental ionization potentials with calculated orbital energies of alkanes and cycloalkanes...
Table 4 Experimental vertical ionization potential IPV (eV) and calculated orbital energies e (eV) for imines 43a-c... Table 4 Experimental vertical ionization potential IPV (eV) and calculated orbital energies e (eV) for imines 43a-c...
Measured Vertical Ionization Potentials (/ ) and Calculated Orbital Energies (—e,) for Some C5H5BeR Compounds ... [Pg.231]

Calculated orbital contraction ratio R / NR as a function of atomic number Z. [Pg.72]


See other pages where Orbital calculations is mentioned: [Pg.393]    [Pg.309]    [Pg.42]    [Pg.44]    [Pg.214]    [Pg.702]    [Pg.28]    [Pg.56]    [Pg.73]    [Pg.9]    [Pg.319]    [Pg.356]    [Pg.240]    [Pg.267]    [Pg.66]    [Pg.125]    [Pg.178]    [Pg.124]    [Pg.297]    [Pg.309]    [Pg.40]   
See also in sourсe #XX -- [ Pg.231 ]




SEARCH



1,3,5-hexatriene molecular orbital calculation

2.3- Pyridyne molecular orbital calculations for

AMI molecular orbital calculation

Ab initio calculations of molecular orbital energies

Ab initio molecular orbital calculations

Acidities, from molecular orbital calculations

Alkylation molecular orbital calculation

Alkynyl molecular orbital calculations

And molecular orbital calculations

Anomeric effect molecular-orbital calculations

Atomic Densities, Polarizabilities, and Natural Orbitals Derived from Generalized Sturmian Calculations

Atomic natural orbitals energy calculations

Atomic orbital calculations, light

Atomic orbital integrals, calculation

Atomic orbital matrix calculation

Atomic orbitals calculating

Atomic orbitals electronic structure calculations

Bonding description molecular orbital calculations

Bonding orbital calculation

CNDO molecular orbital calculations

Calculation of Second-Order Spin-Orbit Effects

Calculation of the photoelectron orbitals

Calculation using molecular orbital

Calculation using molecular orbital theory

Calculations, band theory orbital energies

Carbocations, stability orbital calculation

Closed-shell molecular orbitals calculations

Compression Crystal orbital calculations

Copper complexes molecular orbital calculations

Crystal orbitals, Hartree-Fock calculation basis

Cyclopentenones molecular orbital calculations

D Orbital calculation

DV-Xa molecular orbital calculation

Degenerate orbitals calculation

Dunning basis sets orbital energy calculations using

Dyson orbitals electron propagator calculations

Efficient spin-orbit coupling calculation

Eigenvalues calculations using Slater orbitals

Energy levels molecular orbital calculations

Extended Hiickel molecular orbital calculations

Extended Hiickel molecular orbital method calculation procedure

Extended Huckel molecular orbital calculations, transition metal

Fenske-Hall molecular orbital calculations

Ferrocene molecular orbital calculations

Frontier orbital calculations

Gauge-including atomic orbital calculations

Gauge-including atomic orbitals chemical shift shielding calculation

Gauge-invariant atomic orbital theory shielding calculations

Gaussian basis sets orbital energy calculations using

Gaussian functions orbital energy calculations with

H2O Molecular Orbital Calculation in C2v Symmetry

Hamiltonian atomic orbital integrals, calculation

Heteronuclear diatomic molecule molecular orbital calculations

Highest occupied molecular orbital calculation

Hiickel molecular orbital calculations description

Hiickel molecular orbital calculations, for

Hiickel molecular-orbital calculation

Homonuclear diatomic molecules molecular orbital calculations

Htickel molecular orbital calculation

Huckel molecular orbital calculations

Huckel molecular orbital calculations, extended

Huckel molecular orbital calculations, for

INDO molecular orbital calculation

Initial Detailed Molecular Orbital Calculations

Iodination molecular orbital calculation

MINDO/3 molecular orbital calculations

Mesomeric betaines molecular orbital calculations

Metallocenes molecular orbital calculations

Molecular Orbital Calculations on the

Molecular dynamics orbital calculations

Molecular orbital calculation-constrained

Molecular orbital calculation-constrained electron diffraction

Molecular orbital calculations

Molecular orbital calculations CNDO methods

Molecular orbital calculations Huckel approximations

Molecular orbital calculations bimolecular reactions

Molecular orbital calculations clusters

Molecular orbital calculations conjugation

Molecular orbital calculations dissociation energy

Molecular orbital calculations electronic structures

Molecular orbital calculations ethylene molecules

Molecular orbital calculations for

Molecular orbital calculations gold clusters

Molecular orbital calculations ligand geometry

Molecular orbital calculations limits

Molecular orbital calculations multiple electronic states

Molecular orbital calculations nickel

Molecular orbital calculations of transition state geometries

Molecular orbital calculations organic radical ions

Molecular orbital calculations silver

Molecular orbital calculations singlet carbenes

Molecular orbital calculations solvent effect

Molecular orbital calculations species

Molecular orbital calculations thermochemistry

Molecular orbital calculations titanium

Molecular orbital calculations triplet carbenes

Molecular orbital calculations, acidities

Molecular orbital calculations, gases

Molecular orbital calculations, light

Molecular orbital calculations, light method

Molecular orbital calculations, transition metal

Molecular orbital diagrams, calculated

Molecular orbital theory calculation

Molecular orbital theory properties calculable

Molecular orbitals calculating

Molecular orbitals first principles calculations

Molecular orbitals quantitative calculations

Molecular-orbital calculations 1,2-migrations

Molecular-orbital calculations 1.2- shifts

Molecular-orbital calculations 1.3- dipolar

Molecular-orbital calculations Beckmann rearrangement

Molecular-orbital calculations Claisen rearrangement

Molecular-orbital calculations Diels-Alder reactions

Molecular-orbital calculations Subject

Molecular-orbital calculations acylation rates of amines

Molecular-orbital calculations addition

Molecular-orbital calculations addition reactions

Molecular-orbital calculations allyl systems

Molecular-orbital calculations anionic

Molecular-orbital calculations anions

Molecular-orbital calculations azidopyrrolines

Molecular-orbital calculations aziridines

Molecular-orbital calculations benzobicyclooctadiene

Molecular-orbital calculations benzynes

Molecular-orbital calculations bromination

Molecular-orbital calculations carbanions

Molecular-orbital calculations carbenes

Molecular-orbital calculations complexes

Molecular-orbital calculations cycloaddition

Molecular-orbital calculations cyclopropanes

Molecular-orbital calculations cyclopropene

Molecular-orbital calculations cyclopropenes

Molecular-orbital calculations deprotonation

Molecular-orbital calculations dimerization

Molecular-orbital calculations electrocyclic reactions

Molecular-orbital calculations electrophilic addition

Molecular-orbital calculations electrophilic aromatic

Molecular-orbital calculations elimination reactions

Molecular-orbital calculations formation

Molecular-orbital calculations heterocyclic

Molecular-orbital calculations interconversion

Molecular-orbital calculations isomerizations

Molecular-orbital calculations isotope effects

Molecular-orbital calculations on:

Molecular-orbital calculations pericyclic reactions

Molecular-orbital calculations polymerization

Molecular-orbital calculations protonation

Molecular-orbital calculations reactions

Molecular-orbital calculations rearrangement

Molecular-orbital calculations retro

Molecular-orbital calculations ring opening

Molecular-orbital calculations structure

Molecular-orbital calculations substitution

Molecular-orbital calculations surface

Molecular-orbital calculations tautomerism

Molecular-orbital calculations, nomenclature

Molecular-orbital calculations, pyranose

Molecular-orbital calculations, tailoring

Molybdenum complexes molecular orbital calculations

Numerical solutions calculations using Slater orbitals

Occupied orbitals, calculated

Open-shell molecular orbitals calculations

Orbital Calculations Results

Orbital Calculations and QSARs in Toxicity

Orbital Calculations of the Anomeric Effect

Orbital Theory Calculations

Orbital calculations, extended Huckel

Orbitals calculation

Orbitals calculation

Orbitals, wave-function calculations

Perturbational molecular orbital calculations

Platinum complexes molecular orbital calculations

Quantum chemical calculations semiempirical molecular orbital

Quantum defect orbital calculation method

Radical detection molecular orbital calculations

Rings orbital calculations

Scf molecular orbital calculations

Semi-empirical molecular orbital calculations

Semiempirical molecular orbital calculations

Slater functions orbital energy calculations using

Slater-type orbitals calculations

Spin Hamiltonians calculation from molecular orbitals

Spin-orbit coupling calculations

Spin-orbit coupling numerical calculations

Spin-orbit interaction numerical calculations

Spin-orbit operators calculations

Spin-orbital coupling response theory calculation

Split-valence basis sets orbital energy calculations using

Symmetry, and molecular orbital calculations

The LiH molecule approximate molecular orbital calculations

Two-orbital calculation

Types of Molecular Orbital Calculations

Walsh diagram, orbital calculation

© 2024 chempedia.info