Abstract
As seen in experiments with poly(3-hexylthiophene), substitution of hydrogen with deuterium on the main chain alone decreases crystallinity. To understand this effect, a general formalism for analysis of the dipole moments and polarizabilities incorporating quantum nuclei, is developed. The formalism, based on quantum dynamics of the proton/deuteron and on the perturbative analysis of the dipole interaction energy, accounts for the anharmonicity of a potential energy surface and for the anisotropy of molecular dipole moments. The formalism is implemented within the Discrete Variable Representation and the Density Functional Theory describing, respectively, the quantum proton/deuteron on the thiophene ring and the electronic structure of the 27-atom model polymer chain, embedded into a larger crystalline environment. The isotope effect is mainly attributed to the differences in the zero-point energy of the CH/CD bonds and to the isotope-dependence of the dipole-dipole inter-chain interactions.
Original language | English |
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Article number | e25712 |
Journal | International Journal of Quantum Chemistry |
Volume | 118 |
Issue number | 20 |
DOIs | |
State | Published - Oct 15 2018 |
Funding
Part of this work was conducted at the Center for Nanophase Materials Sciences, a US Department of Energy Office of Science User Facility. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant No. ACI-1548562 (allocation TG-DMR110037), and the HPC cluster, funded by the National Science Foundation under Grant No. CHE-1048629. This material is based upon work supported by the National Science Foundation under Grant Nos. CHE-1056188, CHE-1565985, and OIA-1655740, and by a GEAR grant from SC EPSCoR. National Science Foundation; US Department of Energy Office of Science information National Science Foundation; US Department of Energy Office of SciencePart of this work was conducted at the Center for Nanophase Materials Sciences, a US Department of Energy Office of Science User Facility. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant No. ACI-1548562 (allocation TG-DMR110037), and the HPC cluster, funded by the National Science Foundation under Grant No. CHE-1048629. This material is based upon work supported by the National Science Foundation under Grant Nos. CHE-1056188, CHE-1565985, and OIA-1655740, and by a GEAR grant from SC EPSCoR.
Keywords
- dipole interactions
- isotope effect on crystallinity
- nuclear quantum effects
- perturbation theory
- quantum dynamics