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  2. Hückel method - Wikipedia

    en.wikipedia.org/wiki/Hückel_method

    To summarize, we are assuming that: (1) the energy of an electron in an isolated C(2p z) orbital is =; (2) the energy of interaction between C(2p z) orbitals on adjacent carbons i and j (i.e., i and j are connected by a σ-bond) is =; (3) orbitals on carbons not joined in this way are assumed not to interact, so = for nonadjacent i and j; and ...

  3. Orbit equation - Wikipedia

    en.wikipedia.org/wiki/Orbit_equation

    In astrodynamics, an orbit equation defines the path of orbiting body around central body relative to , without specifying position as a function of time.Under standard assumptions, a body moving under the influence of a force, directed to a central body, with a magnitude inversely proportional to the square of the distance (such as gravity), has an orbit that is a conic section (i.e. circular ...

  4. Atomic orbital - Wikipedia

    en.wikipedia.org/wiki/Atomic_orbital

    The shapes of p, d and f orbitals are described verbally here and shown graphically in the Orbitals table below. The three p orbitals for n = 2 have the form of two ellipsoids with a point of tangency at the nucleus (the two-lobed shape is sometimes referred to as a "dumbbell"—there

  5. Molecular orbital diagram - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital_diagram

    The three dumbbell-shaped p-orbitals have equal energy and are oriented mutually perpendicularly (or orthogonally). The p-orbitals oriented in the z-direction (p z) can overlap end-on forming a bonding (symmetrical) σ orbital and an antibonding σ* molecular orbital. In contrast to the sigma 1s MO's, the σ 2p has some non-bonding electron ...

  6. Orbital mechanics - Wikipedia

    en.wikipedia.org/wiki/Orbital_mechanics

    From a circular orbit, thrust applied in a direction opposite to the satellite's motion changes the orbit to an elliptical one; the satellite will descend and reach the lowest orbital point (the periapse) at 180 degrees away from the firing point; then it will ascend back. The period of the resultant orbit will be less than that of the original ...

  7. Localized molecular orbitals - Wikipedia

    en.wikipedia.org/wiki/Localized_molecular_orbitals

    Localized molecular orbitals are molecular orbitals which are concentrated in a limited spatial region of a molecule, such as a specific bond or lone pair on a specific atom. They can be used to relate molecular orbital calculations to simple bonding theories, and also to speed up post-Hartree–Fock electronic structure calculations by taking ...

  8. Natural bond orbital - Wikipedia

    en.wikipedia.org/wiki/Natural_bond_orbital

    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.

  9. Antibonding molecular orbital - Wikipedia

    en.wikipedia.org/wiki/Antibonding_molecular_orbital

    Antibonding orbitals are often labelled with an asterisk (*) on molecular orbital diagrams. In homonuclear diatomic molecules, σ* (sigma star) antibonding orbitals have no nodal planes passing through the two nuclei, like sigma bonds, and π* (pi star) orbitals have one nodal plane passing through the two nuclei, like pi bonds.