Eigenvalue-following

There were some problems with the eigenvalue following transition-structure routine jumping from one vibrational mode to another. The semiempirical geometry optimization routines work well. 

It uses a linear or quadratic synchronous transit approach to get closer to the quadratic region of the transition state and then uses a quasi-Newton or eigenvalue-following algorithm to complete the optimization. 

At a given internuclear distance energy eigenvalues follow as... 

Fig. 1 a, b. Schematics showing the generation of the density of states for a) molecules and b) solids via the traditional route of determining the energy eigenvalues followed by construction of a density of states diagram... 

Eigenvalue Following (Augmented Hessian or Restricted Step) °... 

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