Dimer method#
The dimer method of Henkelman and Jónsson [DM_HJonsson99] with improvements by Heyden et al. [DM_HBK05] and Kästner and Sherwood [DM_KastnerS08] for estimating the lowest Eigenmode using only first derivatives.
An overview may be found in Olsen et al. [DM_OKH+04].
The dimer separation is set in the [Main] section with the
finiteDifference parameter.
The method of Melander et al. [DM_MLJonsson15] is also implemented for use with gas phase systems.
Note
There is no point removing rotations for an extended system. Rotation removal may be more detrimental as noted in Goswami [DM_Gos25].
Added in version 2.5: The Gaussian Process Regression accelerated dimer in C++ from Goswami et al. [DM_GMK+25].
Configuration#
[Dimer]
References#
Rohit Goswami. Bayesian hierarchical models for quantitative estimates for performance metrics applied to saddle search algorithms. AIP Advances, 15(8):85210, August 2025. doi:10.1063/5.0283639.
Rohit Goswami, Maxim Masterov, Satish Kamath, Alejandro Pena-Torres, and Hannes Jónsson. Efficient Implementation of Gaussian Process Regression Accelerated Saddle Point Searches with Application to Molecular Reactions. Journal of Chemical Theory and Computation, July 2025. doi:10.1021/acs.jctc.5c00866.
Graeme Henkelman and Hannes Jónsson. A dimer method for finding saddle points on high dimensional potential surfaces using only first derivatives. The Journal of Chemical Physics, 111(15):7010–7022, October 1999. doi:10.1063/1.480097.
Andreas Heyden, Alexis T. Bell, and Frerich J. Keil. Efficient methods for finding transition states in chemical reactions: Comparison of improved dimer method and partitioned rational function optimization method. The Journal of Chemical Physics, 123(22):224101, December 2005. doi:10.1063/1.2104507.
Johannes Kästner and Paul Sherwood. Superlinearly converging dimer method for transition state search. The Journal of Chemical Physics, 128(1):014106, January 2008. doi:10.1063/1.2815812.
Marko Melander, Kari Laasonen, and Hannes Jónsson. Removing External Degrees of Freedom from Transition-State Search Methods using Quaternions. Journal of Chemical Theory and Computation, 11(3):1055–1062, March 2015. doi:10.1021/ct501155k.
R. A. Olsen, G. J. Kroes, G. Henkelman, A. Arnaldsson, and H. Jónsson. Comparison of methods for finding saddle points without knowledge of the final states. The Journal of Chemical Physics, 121(20):9776–9792, November 2004. doi:10.1063/1.1809574.