Linear synchronous transit

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. 

Linear synchronous transit followed by quasi-Newton. 

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. 

Linear Synchronous Transit. The name given to procedures which estimate the geometries of transition states based on averages of the geometries of reactants and products, sometimes weighted by the overall thermodynamics of reaction. 

Fig. 9.14 Reaction pathway for photoexcited exTTF—0PPE3-C60 obtained from linear synchronous transit calculations on the optimized geometries of excited states. A possible reaction mechanism is indicated by the blue dotted line and suggests a hole transfer. For further details see text...

Figure 12.10. Potential-energy functions of the S0 state, the locally excited 1 hit states of guanine and cytosine, the lowest1 rnr state, and the tt-jt charge-transfer state of the WC conformer (a), the conformer B (b), and the conformer C (c) of the CG dimer. The PE functions have been calculated along the linear-synchronous-transit proton-transfer reaction path from the S0 minimum to the biradical minimum. Insets show the potential-energy function of the locally excited 1mr state of guanine calculated along the minimum-energy path for stretching of the NH bond...

Carpenter and Borden " first computed two trajectories using direct dynamics on the CASSCF(8,8)/6-31G surface. Both trajectories were initiated at 43, the TS connecting reactant to the diradical intermediate. A linear-synchronous-transit (LST) path was computed connecting 43 to the intermediate 42 and one connecting 43 to 44. The vector corresponding to these two motions was used to assign the phases of the normal modes. The trajectory for the first case (the LST toward the intermediate) did, as expected, end at 42. The second trajectory (the LST towards... 

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. 10.5. Model potential energy surface illustrating linear synchronous transit (LST) and quadratic synchronous transit (QST) paths (from Ref. [72] with permission).

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