Intramolecular charge ordering in the multi molecular orbital system (TTM-TTP)I_3

TL;DR

This study investigates the electronic structure of (TTM-TTP)I_3, revealing it as a two-orbital system with intramolecular charge ordering that influences its low-temperature magnetic properties.

Contribution

The paper introduces an effective model based on ab initio calculations to explain intramolecular charge ordering in (TTM-TTP)I_3, linking electronic structure to magnetic behavior.

Findings

Identified (TTM-TTP)I_3 as a two-orbital system.

Supported intramolecular charge ordering as the origin of symmetry breaking.

Linked charge distribution to low-energy magnetic properties.

Abstract

Starting from the structure of the (TTM-TTP)I_3 molecular-based material, we examine the characteristics of frontier molecular orbitals using ab initio (CASSCF/CASPT2) configurations interaction calculations. It is shown that the singly-occupied and second-highest-occupied molecular orbitals are close to each other, i.e., this compound should be regarded as a two-orbital system. By dividing virtually the [TTM-TTP] molecule into three fragments, an effective model is constructed to rationalize the origin of this picture. In order to investigate the low-temperature symmetry breaking experimentally observed in the crystal, the electronic distribution in a pair of [TTM-TTP] molecules is analyzed from CASPT2 calculations. Our inspection supports and explains the speculated intramolecular charge ordering which is likely to give rise to low-energy magnetic properties.