Energy Ranking of Molecular Crystals Using Density Functional Theory Calculations and an Empirical van der Waals Correction

2005 ◽  
Vol 109 (32) ◽  
pp. 15531-15541 ◽  
Author(s):  
Marcus A. Neumann ◽  
Marc-Antoine Perrin
2019 ◽  
Vol 21 (34) ◽  
pp. 18612-18621 ◽  
Author(s):  
M. Idrees ◽  
H. U. Din ◽  
R. Ali ◽  
G. Rehman ◽  
T. Hussain ◽  
...  

Janus monolayers and their van der Waals heterostuctures are investigated by hybrid density functional theory calculations.


2017 ◽  
Vol 31 (13) ◽  
pp. 1750149 ◽  
Author(s):  
Ling Ding ◽  
Wen-Hui Fan ◽  
Xu Chen ◽  
Ze-You Chen ◽  
Chao Song

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.


2016 ◽  
Vol 18 (18) ◽  
pp. 12920-12927 ◽  
Author(s):  
Ersen Mete ◽  
Ayşen Yılmaz ◽  
Mehmet Fatih Danışman

Isolated and full monolayer adsorption of various carboranethiol (C2B10H12S) isomers on the gold(111) surface has been investigated using both the standard and van der Waals density functional theory calculations.


2018 ◽  
Vol 25 (01) ◽  
pp. 1850038
Author(s):  
AMIRALI ABBASI ◽  
JABER JAHANBIN SARDROODI

Comparison of structural and electronic properties between pristine and N-doped titanium dioxide-(TiO2)/molybdenum disulfide (MoS2) nanocomposites and their effects on the adsorption of thiophene molecule were performed using density functional theory calculations. To correctly estimate the adsorption energies, the van der Waals interactions were taken into account in the calculations. On the TiO2/MoS2 nanocomposite, thiophene molecule tends to be strongly adsorbed by its sulfur atom. The five-fold coordinated titanium atom of TiO2 was found to be an active binding site for thiophene adsorption. The results suggest that the thiophene molecule has not any mutual interaction with MoS2 nanosheet. The electronic structures of the complex systems are discussed in terms of the density of states and molecular orbitals of the thiophene molecules adsorbed to the TiO2/MoS2 nanocomposites. It was also found that the doping of nitrogen atom is conductive to the interaction of thiophene with nanocomposite. Thus, it can be concluded that the interaction of thiophene with N-doped TiO2/MoS2 nanocomposite is more energetically favorable than the interaction with undoped nanocomposite. The sensing capability of TiO2/MoS2 toward thiophene detection was greatly increased upon nitrogen doping. These processes ultimately lead to the strong adsorption of thiophene on the N-doped TiO2/MoS2 nanocomposites, indicating potential applicability of these nanocomposites as novel gas sensors.


RSC Advances ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 42-52
Author(s):  
M. Munawar ◽  
M. Idrees ◽  
Iftikhar Ahmad ◽  
H. U. Din ◽  
B. Amin

Using density functional theory calculations, we have investigated the electronic band structure, optical and photocatalytic response of BSe, M2CO2 (M = Ti, Zr, Hf) monolayers and their corresponding BSe–M2CO2 (M = Ti, Zr, Hf) van der Waals heterostructures.


Crystals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 243 ◽  
Author(s):  
Qing Peng ◽  
Guangyu Wang ◽  
Gui-Rong Liu ◽  
Suvranu De

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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