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Dissonant counterpoint was originally theorized by Charles Seeger as "at first purely a school-room discipline," consisting of species counterpoint but with all the traditional rules reversed. First species counterpoint must be all dissonances, establishing "dissonance, rather than consonance, as the rule," and consonances are "resolved ...
Counterpoint (Kontrapunkt in the original German) is the second volume of Heinrich Schenker's New Musical Theories and Fantasies (the first is Harmony and the third is Free Composition). It is divided into two "Books", the first published in 1910, and the second in 1922. The subject matter of the work is species counterpoint.
In spectroscopy, a forbidden mechanism (forbidden transition or forbidden line) is a spectral line associated with absorption or emission of photons by atomic nuclei, atoms, or molecules which undergo a transition that is not allowed by a particular selection rule but is allowed if the approximation associated with that rule is not made. [1]
In the first place, Clar's rule is formulated only for species with hexagonal rings, [12] and thus it cannot be applied to species having rings different from the benzene moiety, even though an extension of the rule to molecules with rings of any dimension has been provided by Glidewell and Lloyd. [12]
For Möbius systems there is an odd number of plus–minus sign inversions in the basis set in proceeding around the cycle. A circle mnemonic [3] was advanced which provides the MO energies of the system; this was the counterpart of the Frost–Musulin mnemonic [6] for ordinary Hückel systems.
Complementing the Laporte rule, is the spin-selection rule, which forbids transitions that involve changes in spin state. Violations of both the Laporte and spin-selection rules results in particularly low extinction coefficients. Illustrative of this combined effect is the faintness of even concentrated solutions of octahedral Mn(II) and Fe ...
Tolman's rule states that, in a certain chemical reaction, the steps involve exclusively intermediates of 18- and 16 electron configuration. The rule is an extension of the 18-electron rule . This rule was proposed by American chemist Chadwick A. Tolman . [ 1 ]
The Lennard-Jones Potential is a mathematically simple model for the interaction between a pair of atoms or molecules. [3] [4] One of the most common forms is = [() ()] where ε is the depth of the potential well, σ is the finite distance at which the inter-particle potential is zero, r is the distance between the particles.