Understanding Molecular Crystals with Dispersion-Inclusive Density Functional Theory: Pairwise Corrections and Beyond

We report, for the first time to our knowledge, the terahertz (THz) spectra of isonicotinic acid and 2-picolinic acid. The distinct THz spectral differences among these two isomers and nicotinic acid have also been observed, indicating that the THz vibrational modes are highly sensitive to the structural differences even in similar molecular crystals. Besides, solid-state density functional theory calculations reveal better qualitative agreement with the measured absorption features, which are related to the molecular vibrations of nicotinic acid and isonicotinic acid. As for 2-picolinic acid, the calculation based on the primitive cell reproduces the absorption features at 1.46, 1.82 and 2.46 THz originating from intermolecular vibrations. These results suggest that THz spectra can identify the complex intermolecular interactions even in similar molecular crystals, which shows potential applications in identifying isomers in food and pharmaceutical production.

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Assessment of van der Waals inclusive density functional theory methods for layered electroactive materials

Physical Chemistry Chemical Physics ◽

10.1039/c7cp00284j ◽

2017 ◽

Vol 19 (15) ◽

pp. 10133-10139 ◽

Cited By ~ 26

Author(s):

Ariel Lozano ◽

Bruno Escribano ◽

Elena Akhmatskaya ◽

Javier Carrasco

Keyword(s):

Density Functional Theory ◽

High Throughput ◽

Density Functional ◽

Van Der Waals ◽

Functional Theory ◽

Electroactive Materials ◽

Computational Screening ◽

Inclusive Density ◽

Selection Of

This work provides solid guidance for the selection of accurate and robust vdW-inclusive methods for high-throughput computational screening of layered electroactive materials.

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Modified Corrections for London Forces in Solid-State Density Functional Theory Calculations of Structure and Lattice Dynamics of Molecular Crystals

The Journal of Physical Chemistry A ◽

10.1021/jp303746a ◽

2012 ◽

Vol 116 (25) ◽

pp. 6927-6934 ◽

Cited By ~ 20

Author(s):

Matthew D. King ◽

Timothy M. Korter

Keyword(s):

Density Functional Theory ◽

Solid State ◽

Lattice Dynamics ◽

Density Functional ◽

Molecular Crystals ◽

Density Functional Theory Calculations ◽

State Density ◽

Functional Theory

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Van der Waals Density Functional Theory vdW-DFq for Semihard Materials

Crystals ◽

10.3390/cryst9050243 ◽

2019 ◽

Vol 9 (5) ◽

pp. 243 ◽

Cited By ~ 8

Author(s):

Qing Peng ◽

Guangyu Wang ◽

Gui-Rong Liu ◽

Suvranu De

Keyword(s):

Density Functional Theory ◽

Energetic Materials ◽

Density Functional ◽

Energetic Material ◽

Van Der Waals ◽

Molecular Crystals ◽

Soft Materials ◽

Dispersion Force ◽

Electronic Charge ◽

Functional Theory

There are a large number of materials with mild stiffness, which are not as soft as tissues and not as strong as metals. These semihard materials include energetic materials, molecular crystals, layered materials, and van der Waals crystals. The integrity and mechanical stability are mainly determined by the interactions between instantaneously induced dipoles, the so called London dispersion force or van der Waals force. It is challenging to accurately model the structural and mechanical properties of these semihard materials in the frame of density functional theory where the non-local correlation functionals are not well known. Here, we propose a van der Waals density functional named vdW-DFq to accurately model the density and geometry of semihard materials. Using β -cyclotetramethylene tetranitramine as a prototype, we adjust the enhancement factor of the exchange energy functional with generalized gradient approximations. We find this method to be simple and robust over a wide tuning range when calibrating the functional on-demand with experimental data. With a calibrated value q = 1.05 , the proposed vdW-DFq method shows good performance in predicting the geometries of 11 common energetic material molecular crystals and three typical layered van der Waals crystals. This success could be attributed to the similar electronic charge density gradients, suggesting a wide use in modeling semihard materials. This method could be useful in developing non-empirical density functional theories for semihard and soft materials.

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