Automated Exploration of Chemical Reaction Pathways
GRRM ∼Global Reaction Route Mapping∼

GRRM developed by K. Ohno and S. Maeda enables one to follow all reaction pathways from an equilibrium (EQ) point towards structures of transition states (TS) surrounding the EQ point. Subsequent downward followings from already found TSs can easily be made as conventional intrinsic reaction coordinate (IRC) followings to reach some EQ points and dissociation channels (DC).

GRRM innovates compound synthesis method by automated exploration of chemical reaction pathways based on precise quantum chemistry calculation.

Theory

N-atoms system has 3N-6 dimensional potential energy surfaces(PES).

Reaction pathways follows the direction that ADD in PES increases.

The pathways around EQ can be discovered at minima on the scaled hypersphere which would have a constant energy when the potentials are harmonic.

Feature

Cooperating with quantum chemistry programs such as Gaussian 03/09 and Molpro, GRRM enables one to perform high speed exploration of chemical reaction pathways in 3N-6 dimensional potential energy surfaces (which was previously limited to 4 atoms) by scaled hypersphere search (SHS) method which is based on anharmonic downward distortion (ADD).

Functions

Optimization of EQ: EQ structures can be optimized by SIRFO and BFGS methods.
Optimization of TS: TS structures can be optimized by SIRFO and Bofill’s methods.
IRC search: IRC can be traced by Page and McIver methods.
One step TS search: An efficient search of via a TS between a reactant and a product without any initial guess.
Intermediate search: Hipershpere-contraction-mode SHS enables one to explore the multi-step reaction pathways.
Excited-state analysis: Minimum energy points on seems ofcrossings can be searched. With a help of Molpro, excited potential energy surfaces can be searched more effectively.
Large ADD following (LADD): A very efficient (1/5∼1/10) search of lower lying structures can be made by the LADD algorithm.
ONIOM and various QM&MM methods: ONIOM as well as various methods available in the Gaussian program can be used as options in combination with the above techniques.
Microiteration: In connection with QM&MM, the microiteration technique can be used to reduce the computational demands drastically, and it extends the range of application of GRRM considerably.

How to obtain GRRM

Free of charge for academic users. HPC SYSTEMS Inc. sells GRRM-ready servers.

GRRM Free Trial

GRRM Free Trial is provided for the purpose of promotion of research use and industry use of GRRM.
It is only for people who are intended to actually use GRRM.
→here

Examples

GRRM of CH₃NO system	Exploring Glycine synthesis pathways	Designing Alanine D-L conversion pathways
Multistep reaction pathways of C₂₀ cluster	Stereoselectivity catalyst on Chiral system	Structural transition of protonated H₂O octet cluster

HPC SYSTEMS Inc.

High Performance Computing, Computational Chemistry Solution Company