期刊
MATERIALS CHEMISTRY AND PHYSICS
卷 175, 期 -, 页码 138-145出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.matchemphys.2016.03.003
关键词
Organic compounds; Ab initio calculations; Thermal expansion; Thermodynamic properties
资金
- National Natural Science Foundation of China (NSFC) [51502010, 51572010, 51472017]
The thermodynamic properties and negative thermal expansion (NTE) behavior of metal-organic framework MOF-5 are investigated within the quasi-harmonic approximation, by using density functional theory. For nanoporous MOF-5, the temperature dependence of bulk modulus increases with increasing temperature, indicating that the resistance to compression is enhanced gradually. The large NTE behavior is obtained, which agrees reasonably with the experimental data. From the Gruneisen parameter as a function of temperature, it can be found that low-frequency phonons are closely associated with the NTE of MOF-5. The corresponding vibrational modes can be viewed as the results of local deformations (translation, rotation, twisting) of BDC (1,4-benzenedicarboxylate) linker and zinc clusters. The lowest-frequency phonon mode (the transverse motion of carboxylate groups and benzene ring, zinc clusters being as rigid units) is confirmed to be most responsible for thermal contraction. (C) 2016 Elsevier B.V. All rights reserved.
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