Dimer

The dimer method of Henkelman and Jónsson with improvements by Heyden et al and Kästner and Sherwood for estimating the lowest eigenmode using only first derivatives. [1] [2] [3]

The dimer separation is set in the [Main] section with the finiteDifference parameter.

[Dimer] Options

opt_method: Optimization algorithm to choose the dimer rotation direction

default: cg

options:

sd: steepest descent, rotate along the rotational force.

cg: conjugate gradient, rotate along conjugate directions.

lbfgs: Limited memory Broyden-Fletcher-Goldfarb-Shanno Quasi-Newton optimizer.

converged_angle: The dimer is considered converged if it will be rotated fewer degrees than this angle.

default: 5.0

rotations_max: This is the maximum number of rotations allowed for the dimer for each minimum mode estimation.

default: 10

References

[1]	Henkelman and H. Jónsson, “A dimer method for finding saddle points on high dimensional potential surfaces using only first derivatives,” J. Chem. Phys. 111, 7010-7022 (1999). DOI

[2]	Heyden, A.T. Bell, and F.J. Keil, “Efficient methods for finding transition states in chemical reactions: Comparison of improved dimer method and partitioned rational function optimization method,” J. Chem. Phys. 123, 224101 (2005). DOI

[3]	Kästner and P. Sherwood, “Superlinearly converging dimer method for transition state search,” J. Chem. Phys. 128, 014106 (2008) DOI