GRRM®20

Kinetic simulations / kinetics-based navigations using RCMC

A kinetic analysis method, rate constant matrix contraction (RCMC), which is applicable to complex reaction path networks is available in GRRM®20. RCMC can be used in two purposes: (1) as a kinetic navigation of the SC-AFIR search, and (2) analysis of a reaction path network obtained by a SC-AFIR search. The kinetic navigation enables to perform an on-the-fly kinetic simulation of a given chemical system under an experimental condition (reaction temperature and reaction time). The latter allows to coarse-grain a reaction path network, to compute an overall rate constant between the reactant and the product, to extract the kinetically most feasible path from a reaction path network, and so on.

Periodic boundary conditions (PBCs)

Geometry optimization, reaction path calculation, and automated reaction path exploration under PBCs are possible in GRRM®20. When translational vectors are specified as active, both translational vectors and atom positions are optimized simultaneously. In addition, an automated search for paths of reactions on a 2D/1D slab model can also be performed by fixing all or some of translational vectors.

Optimizer for large systems over 500 atoms

An optimization algorithm for systems including a large number of active variables is available in GRRM®20. The algorithm performs a geometry optimization in the full dimension using a limited dimensional PES expressed by gradient vectors obtained during the optimization. Its performance was tested with systems including up to 1000 atoms in combination with a semi-empirical quantum chemical calculation method.

Massive parallelizations

In GRRM®20, parallelization efficiency of SC-AFIR calculations was improved significantly. Various jobs that execute 100-500 path calculations simultaneously have been done in the developer group. In these jobs, several cores have been used in each path calculation, and thus the total numbers of cores used in these jobs have been 1000~2000.

Speedups

Many fine optimizations and speedups have been made, backed by the state-of-the-art practical achievements of GRRM® developers.

Interface for changing AFIR search method from the outside

With a simple external script, you can use the option to reflect informatics methods and empirical rules in the search procedure, and users can also participate in the development of methods for accelerating automatic search.

Applicable for various R&D

GRRM®20 can be applied to various reaction systems such as organic reaction, organometallic catalysis, cluster catalysis, radical reaction, photoreaction involving electronic excited states, crystal phase transition under periodic boundary conditions, enzyme catalysis described by QM/MM-ONIOM method, and so on.

For example, drug synthesis. By clarifying all reaction pathways that can synthesize the desired drug molecule, it can be used for catalyst design for rate-determining reactions and suppression of by-products.

For example, designing luminescent materials. Since the stability of the material can be considered from the viewpoint of reaction, it can be used for designing long-life materials that emit stable light.

For example, a combustion reaction. Thousands and tens of thousands of elementary reactions can be obtained based on highly accurate quantum chemistry calculations, so it is possible to meet the accuracy of reaction speed in car and rocket engine design CAE.