High performance global exploration of isomers and isomerization channels on quantum chemical potential energy surface of H₅C₂NO₂

Abstract

High performance global exploration of isomers and isomerization channels on the quantum chemical potential energy surface (PES) is performed for H 5 C 2 NO 2 by using the scaled hypersphere search-anharmonic downward distortion following (SHS-ADDF) method. A multi-node operation, NeoGRRM, has achieved high performance exploration calculations for the large system by submitting SHS-ADDF sub-jobs into many cores in parallel and unifying the results of sub-jobs into the total lists of the main-job. Global exploration of equilibrium (EQ) and transition-state structures at the level of B3LYP/6-31G(d) gave 3210 EQs and 23278 TSs. Nine compounds were found in the low energy regions of 0-100 kJ/mol; the lowest energy compound is Nmethylcarbamic acid, the second is methyl carbamate, and the third is glycine (the most fundamental amino acid). Interconversion pathways between the conformers of each of the low energy compounds were surveyed. Isomerization channels around glycine were explored in detail. The lowest energy barriers around some of the EQs turned to be negative after zero-point energy corrections. This indicates that those structures cannot exist as independent structures because they spontaneously collapse into more stable structures. The global PES search showed various interesting dissociating channels which indicate synthon reaction pathways in the reverse directions.

A highly accurate full-dimensional ab initio potential surface for the rearrangement of methylhydroxycarbene (H3C–C–OH)

“…In this work, we constructed a highly accurate global PES [23][24][25][26][27][28][29][30] using the fundamental invariant neural network (FI-NN) method, 31 based on over high-level 90 000 data points. The constructed PES covers all the 1t rearrangement processes (Fig.…”

Global Search for Stable C4H5NO Compounds—Guinness Molecules and Stability Islands

“…It can be used for reaction route mapping for the potential surface of a certain chemical formula. Starting from an equilibrium structure, an automated search of dissociation and isomerization reactions can be performed [ 6 , 7 , 8 , 9 , 10 ].…”