Ab initio study on (CO₂)_n clusters via electrostatics- and molecular tailoring-based algorithm

Abstract

An algorithm based on molecular electrostatic potential (MESP) and molecular tailoring approach (MTA) for building energetically favorable molecular clusters is presented. This algorithm is tested on prototype (CO₂)_n clusters with n = 13, 20, and 25 to explore their structure, energetics, and properties. The most stable clusters in this series are seen to show more number of triangular motifs. Many-body energy decomposition analysis performed on the most stable clusters reveals that the 2-body is the major contributor (>96%) to the total interaction energy. Vibrational frequencies and molecular electrostatic potentials are also evaluated for these large clusters through MTA. The MTA-based MESPs of these clusters show a remarkably good agreement with the corresponding actual ones. The most intense MTA-based normal mode frequencies are in fair agreement with the actual ones for smaller clusters. These calculated asymmetric stretching frequencies are blue-shifted with reference to the CO₂ monomer.