Seminar 31/03/17: Breeding new methods for finding first order saddle points

Breeding new methods for finding first order saddle points
Carlos Argáez
University of Iceland
Friday 31 March 2017
3.30pm, Room KE2-008, 2nd Floor, Main Building, DIT Kevin Street

Abstract:

The minimum mode following method for finding first order saddle points on an energy surface is used, for example, in simulations of long time scale evolution of materials and surfaces of solids. Such simulations are increasingly being carried out in combination with computationally demanding electronic structure calculations of atomic interactions, so it is essential to reduce as much as possible the number of chemical-function evaluations needed to find the relevant saddle points. Several improvements to the method are discussed here. Among the new advantages of this method, minimization method is used here: the minimum mode is estimated using the Davidson method with a new coupling on the Hessian approximation. Significant savings in the number of function evaluations can be obtained by assuming the minimum mode is unchanged until the atomic displacement exceeds a threshold value. In total, with this new breed the number of function evaluations is reduced to less than a third with the improved method as compared with the best previously reported results.