Quantifying thermal disorder in metal-organic frameworks: Lattice dynamics and molecular dynamics simulations of hybrid formate perovskites

Katrine L. Svane, Aron Walsh

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Hybrid organic.inorganic materials are mechanically soft, leading to large thermoelastic effects which can affect properties such as electronic structure and ferroelectric ordering. Here we use a combination of ab initio lattice dynamics and molecular dynamics to study the finite temperature behavior of the hydrazinium and guanidinium formate perovskites, [NH2NH3][Zn(CHO2)3] and [C-(NH2)3][Zn(CHO2)3]. Thermal displacement parameters and ellipsoids computed from the phonons and from molecular dynamics trajectories are found to be in good agreement. The hydrazinium compound is ferroelectric at low temperatures, with a calculated spontaneous polarization of 2.6 μC cm-2, but the thermal movement of the cation leads to variations in the instantaneous polarization and eventually breakdown of the ferroelectric order. Contrary to this the guanidinium cation is found to be stationary at all temperatures; however, the movement of the cage atoms leads to variations in the electronic structure and a renormalization in the bandgap from 6.29 eV at 0 K to an average of 5.96 eV at 300 K. We conclude that accounting for temperature is necessary for quantitative modeling of the physical properties of metal-organic frameworks.

Original languageEnglish
Pages (from-to)421-429
Number of pages9
JournalJournal of Physical Chemistry C
Volume121
Issue number1
DOIs
Publication statusPublished - 2017 Jan 1

Fingerprint

formic acid
Lattice vibrations
formates
perovskites
Molecular dynamics
Metals
hydrazinium compounds
disorders
molecular dynamics
Ferroelectric materials
Guanidine
Computer simulation
metals
electronic structure
Electronic structure
Cations
cations
inorganic materials
simulation
Positive ions

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Cite this

@article{360f21ab28b644fc920ee7e4451f4a20,
title = "Quantifying thermal disorder in metal-organic frameworks: Lattice dynamics and molecular dynamics simulations of hybrid formate perovskites",
abstract = "Hybrid organic.inorganic materials are mechanically soft, leading to large thermoelastic effects which can affect properties such as electronic structure and ferroelectric ordering. Here we use a combination of ab initio lattice dynamics and molecular dynamics to study the finite temperature behavior of the hydrazinium and guanidinium formate perovskites, [NH2NH3][Zn(CHO2)3] and [C-(NH2)3][Zn(CHO2)3]. Thermal displacement parameters and ellipsoids computed from the phonons and from molecular dynamics trajectories are found to be in good agreement. The hydrazinium compound is ferroelectric at low temperatures, with a calculated spontaneous polarization of 2.6 μC cm-2, but the thermal movement of the cation leads to variations in the instantaneous polarization and eventually breakdown of the ferroelectric order. Contrary to this the guanidinium cation is found to be stationary at all temperatures; however, the movement of the cage atoms leads to variations in the electronic structure and a renormalization in the bandgap from 6.29 eV at 0 K to an average of 5.96 eV at 300 K. We conclude that accounting for temperature is necessary for quantitative modeling of the physical properties of metal-organic frameworks.",
author = "Svane, {Katrine L.} and Aron Walsh",
year = "2017",
month = "1",
day = "1",
doi = "10.1021/acs.jpcc.6b10714",
language = "English",
volume = "121",
pages = "421--429",
journal = "Journal of Physical Chemistry C",
issn = "1932-7447",
publisher = "American Chemical Society",
number = "1",

}

TY - JOUR

T1 - Quantifying thermal disorder in metal-organic frameworks

T2 - Lattice dynamics and molecular dynamics simulations of hybrid formate perovskites

AU - Svane, Katrine L.

AU - Walsh, Aron

PY - 2017/1/1

Y1 - 2017/1/1

N2 - Hybrid organic.inorganic materials are mechanically soft, leading to large thermoelastic effects which can affect properties such as electronic structure and ferroelectric ordering. Here we use a combination of ab initio lattice dynamics and molecular dynamics to study the finite temperature behavior of the hydrazinium and guanidinium formate perovskites, [NH2NH3][Zn(CHO2)3] and [C-(NH2)3][Zn(CHO2)3]. Thermal displacement parameters and ellipsoids computed from the phonons and from molecular dynamics trajectories are found to be in good agreement. The hydrazinium compound is ferroelectric at low temperatures, with a calculated spontaneous polarization of 2.6 μC cm-2, but the thermal movement of the cation leads to variations in the instantaneous polarization and eventually breakdown of the ferroelectric order. Contrary to this the guanidinium cation is found to be stationary at all temperatures; however, the movement of the cage atoms leads to variations in the electronic structure and a renormalization in the bandgap from 6.29 eV at 0 K to an average of 5.96 eV at 300 K. We conclude that accounting for temperature is necessary for quantitative modeling of the physical properties of metal-organic frameworks.

AB - Hybrid organic.inorganic materials are mechanically soft, leading to large thermoelastic effects which can affect properties such as electronic structure and ferroelectric ordering. Here we use a combination of ab initio lattice dynamics and molecular dynamics to study the finite temperature behavior of the hydrazinium and guanidinium formate perovskites, [NH2NH3][Zn(CHO2)3] and [C-(NH2)3][Zn(CHO2)3]. Thermal displacement parameters and ellipsoids computed from the phonons and from molecular dynamics trajectories are found to be in good agreement. The hydrazinium compound is ferroelectric at low temperatures, with a calculated spontaneous polarization of 2.6 μC cm-2, but the thermal movement of the cation leads to variations in the instantaneous polarization and eventually breakdown of the ferroelectric order. Contrary to this the guanidinium cation is found to be stationary at all temperatures; however, the movement of the cage atoms leads to variations in the electronic structure and a renormalization in the bandgap from 6.29 eV at 0 K to an average of 5.96 eV at 300 K. We conclude that accounting for temperature is necessary for quantitative modeling of the physical properties of metal-organic frameworks.

UR - http://www.scopus.com/inward/record.url?scp=85019418485&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85019418485&partnerID=8YFLogxK

U2 - 10.1021/acs.jpcc.6b10714

DO - 10.1021/acs.jpcc.6b10714

M3 - Article

AN - SCOPUS:85019418485

VL - 121

SP - 421

EP - 429

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 1

ER -