Linear synchronous transit method

HyperChein has two synch ron ons transit meth ods im piemen ted. The linear synchronous transit method (LST) searches for a maximum along a linear path between reactants and products. It may happen that this method will end up with a structure having two or more negative eigenvalues. The quadratic synchronous transit method (QSTlisan improvement of LST approach and searches for a maximum along a parabola connecting reactants and products, and for a minimum in all directions perpendicular to the parabola. 

FIGURE 17.3 Illustration of the linear synchronous transit method for generating a starting point for a transition-structure optimization. 

The Linear Synchronous Transit (LST) method forms the geometry difference vector between the reactant and product, and locates the highest energy structure along this line. The assumption is that all variables change at the same rate along tire reaction path. 

Figure 14.5 Illustration of the linear and quadratic synchronous transit methods. Energy maxima and minima are denoted by and , respectively...

Linear Synchronous Transit (LST) Parametric Method Number 3 (MNDO- Orbital contraction, relativisric effect, 204 Pseudopotential, 171 ... 

To find the activated complex, a convenient method is the so-called linear synchronous transit (LST) method (Halgren and Lipscomb, 1977). In this method, the two stable end-member geometries are interpolated to produce a simple reaction coordinate. In the LST scheme the reaction coordinate, /(0c/ 1), is essentially an interpolation parameter between the interatomic... 

Another interpolation method using structural information from the reactant and product minima is linear synchronous transit (LST) [139]. These two points on the PES... 

Fig. 4. The linear synchronous transit (LST) and quadratic synchronous transit (QST) methods for finding transition structures R, reactants P, prc ucts TS, true transition structure 1, maximum on LST path (full curveV, 2, minimum perpendicular to LST path 3, maximum on QST path (broken curve). The model surface is constructed from two...

In HyperChem, two different methods for the iocation of transition structures are available. The eigenvector following method is appropriate for unimolecuiar processes or any molecular system where a natural vibrational mode of the system tends to lead to a transition state. Synchronous transit methods are especially useful when reactant and product systems are very different, or In cases where It Is desirable to specify a sequence of structures intermediate between reactants and products. Both linear and quadratic synchronous transit methods have been implemented in HyperChem. 

Linear dependence of basis functions, 164 Linear response function, 261 Linear scaling techniques, 80 Linear Synchronous Transit (LST) optimization method, 328 Local Density Approximation (LDA), Local Spin Density Approximation (LSDA) functionals, 182 Local minimum, 339 Localized Molecular Orbitals (LMO), 227 Localized orbital methods, 227 Localized Orbital/local oRiGin (LORG), for calculating magnetic properties, 252 Locally Updated Planes (LUP) optimization method, 330... 

Illustrating the Concepts 264 11.1 Geometry Convergence 264 11.1.1 Ah Initio Methods 264 11.1.2 DFT Methods 267 14.4 Choice of Coordinates 322 14.5 Transition Structure Optimization 327 14.5.1 Methods Based on Interpolation Between Reactant and Product 327 14.5.2 Linear and Quadratic Synchronous Transit 328... 

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