Global Reaction Route Mapping on Potential Energy Surfaces of Formaldehyde, Formic Acid, and Their Metal-Substituted Analogues

Abstract

Global reaction route mapping of equilibrium structures, transition structures, and their connections on potential energy surface (PES) has been done for MCHO (M = H, Li, Na, Al, Cu) and HCO2M (M = H, Li). A one-after-another technique based on the scaled hypersphere search method has been successfully applied to exploring unknown chemical structures, transition structures, and reaction pathways for organometallic systems. Upon metal substitution, considerable changes of stable structures, reaction pathways, and relative heights of transition structures have been discovered, though some features are similar among the analogues. Al and Cu atoms were found to behave as very strong scissors to cut the CO double bond in MCHO. Energy profiles of the CO insertion into Li-H and Li-CH3 bonds were found to be very similar, especially around the structures where the Li atom is not directly connected with the methyl group, which indicates little effects of alkyl substitution on the reaction route topology.

Temperature, composition, and hydrogen isotope effect in the hydrogenation of CO on amorphous ice surface at 10–20K

“…In the gas phase, the activation energy of the above process was calculated to be 320.7 kJ/ mol. 42 That is, this process is thermally allowed when the vibrational level of H 2 is larger than 8. The H 2 molecules are normally vibrationally pumped at the formation via the H-H recombination, because the heat of re- action is as large as 431.3 kJ/ mol.…”

Analyses of bifurcation of reaction pathways on a global reaction route map: A case study of gold cluster Au5

“…[2][3][4] A concept of global reaction route mapping (GRRM) has been established as the approach to explore chemical reaction pathways automatically through a combination of ADDF and IRC computations. In this paper, the "global map" stands for a map of IRC paths obtained by the ADDF method.…”

The effect of Mg2+ incorporation on the structure of calcium carbonate clusters: investigation by the anharmonic downward distortion following method

“…Thus, the large-ADD (l-ADD) technique is available for fast searches in ADDF, which is expected to explore the low energy structures along low barrier pathways 31 ; it has been successfully applied to various systems 27,28,31 and is applied also in the present study. The methods used to efficiently find maximal ADD directions in multi-dimensional potential-energy surfaces and the methods used to effectively choose l-ADDs from various ADDs have been described in previous papers [21][22][23][24]31 .…”

“…Therefore, in the present study, we use the anharmonic downward distortion following (ADDF) method [21][22][23][24] to make quantum chemical calculations intended to investigate the stable structure of Mg-containing calcium carbonate clusters. The ADDF method was recently developed to make an automated global exploration for reaction pathways on the quantum chemical potential energy surface (PES) of a given chemical formula possible without any assumptions of initial structures and reaction routes.…”