Molecular mechanics—valence

For this reason, there has been much work on empirical potentials suitable for use on a wide range of systems. These take a sensible functional form with parameters fitted to reproduce available data. Many different potentials, known as molecular mechanics (MM) potentials, have been developed for ground-state organic and biochemical systems [58-60], They have the advantages of simplicity, and are transferable between systems, but do suffer firom inaccuracies and rigidity—no reactions are possible. Schemes have been developed to correct for these deficiencies. The empirical valence bond (EVB) method of Warshel [61,62], and the molecular mechanics-valence bond (MMVB) of Bemardi et al. [63,64] try to extend MM to include excited-state effects and reactions. The MMVB Hamiltonian is parameterized against CASSCF calculations, and is thus particularly suited to photochemistry. 

Eckart conditions, Renner-Teller effect, triatomic molecules, 610-615 Ehrenfest dynamics, direct molecular dynamics error sources, 403—404 Gaussian wavepacket propagation, 378-383 molecular mechanics valence bond (MMVB), 409-411... 

Molecular mechanics valence bond (MMVB) conical intersection location, 489—490 direct molecular dynamics ... 

Molecular mechanics-valence bond dynamics have been used to study the model 4 + 4-photocycloadditions of butadiene with butadiene. The photoirradiation of t-butyl 9-anthroate and furan produces a mixture of 4 + 4-cycloadduct and 4 - - 4-cyclodimers. 

M. J. Bearpark, F. Bernardi, M. Olivucci, and M. A. Robb, Chem. Phys. Lett., 217, 513 (1994). Molecular Mechanics—Valence Bond Methods for Large Active Spaces Application to Conjugated Polycyclic Hydrocarbons. 

Molecular mechanics-valence bond dynamics have been used to study the model 4 +... 

Nicholas JB, Vance R, Martin E, Burke BJ, Hopfinger AJ (1991) A molecular mechanics valence force field for sulfonamides derived by ab initio methods. J Phys Chem 95 9803-9811... 

Bearpark MJ, Bemardi F, Ohvucci M, Rohh MA. Benchmarking the molecular mechanics valence bond method photophysics of styrene and indene. J Phys Chem A. 1997 101 8395-8401. 

Bearpark M, Robb M, Bernard F, Olivucci M (1994) Molecular mechanics valence-bond methods for large active spaces—application to conjugated polycyclic-hydrocarbons. Chem Phys Lett 217 513... 

Valence-bond ideas are also employed within the molecular mechanics valence bond (MMVB) approach [50, 51, 53, 134, 135, 176-180]. It was originally developed to mimic CASSCF calculations for ground and excited states of conjugated... 

Bearpark MJ et al (2006) Excited states of conjugated hydrocarbons using the molecular mechanics-valence bond (MMVB) method Conical intersections and dynamics. Theor Chem Acc 116 670-682... 

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