Adsorption of NH3and H2O in Acidic Chabazite. Comparison of ONIOM Approach with Periodic Calculations

2005 ◽  
Vol 109 (8) ◽  
pp. 3539-3545 ◽  
Author(s):  
Xavier Solans-Monfort ◽  
Mariona Sodupe ◽  
Vicenç Branchadell ◽  
Joachim Sauer ◽  
Roberto Orlando ◽  
...  
Nanoscale ◽  
2021 ◽  
Author(s):  
Guang Yang ◽  
Shang-Peng Gao

A highly feasible method to restore the intrinsic optical properties of 2D materials in supercell calculations was formulated and applied.


Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1374
Author(s):  
Mariela M. Nolasco ◽  
Catarina F. Araujo ◽  
Pedro D. Vaz ◽  
Ana M. Amado ◽  
Paulo Ribeiro-Claro

The present work emphasizes the value of periodic density functional theory (DFT) calculations in the assessment of the vibrational spectra of molecular crystals. Periodic calculations provide a nearly one-to-one match between the calculated and observed bands in the inelastic neutron scattering (INS) spectrum of crystalline 4-phenylbenzaldehyde, thus validating their assignment and correcting previous reports based on single molecule calculations. The calculations allow the unambiguous assignment of the phenyl torsional mode at ca. 118–128 cm−1, from which a phenyl torsional barrier of ca. 4000 cm−1 is derived, and the identification of the collective mode involving the antitranslational motion of CH···O bonded pairs, a hallmark vibrational mode of systems where C-H···O contacts are an important feature.


2005 ◽  
Vol 1 (4) ◽  
pp. 277-287 ◽  
Author(s):  
B. Collignon ◽  
P.N.M. Hoang ◽  
S. Picaud ◽  
J.C. Rayez

Clustering of water molecules on model soot particles is studied by means of quantum calculations based on the ONIOM approach. The soot particles are modeled by anchoring OH or COOH groups on the face side or on the edges of a graphite crystallite of nanometer size. The quantum calculations aim at characterizing the adsorption properties (structure and adsorption energy) of small water aggregates containing up to 5 water molecules, in order to better understand at a molecular level the role of these OH and COOH groups on the behavior with respect to water adsorption of graphite surface modelling soot emitted by aircraft.


2016 ◽  
Vol 22 (5) ◽  
Author(s):  
Nguyen Minh Thong ◽  
Thi Chinh Ngo ◽  
Duy Quang Dao ◽  
Tran Duong ◽  
Quoc Tri Tran ◽  
...  

2006 ◽  
Vol 62 (5) ◽  
pp. 875-888 ◽  
Author(s):  
Andrew E. Whitten ◽  
Mark A. Spackman

X-ray diffraction data cannot provide anisotropic displacement parameters (ADPs) for H atoms, a major outstanding problem in charge-density analysis of molecular crystals. Although neutron diffraction experiments are the preferred source of this information, for a variety of reasons they are possible only for a minority of materials of interest. To date, approximate procedures combine rigid-body analysis of the molecular heavy-atom skeleton, based on ADPs derived from the X-ray data, with estimates of internal motion provided by spectroscopic data, analyses of neutron diffraction data on related compounds, or ab initio calculations on isolated molecules. Building on these efforts, an improved methodology is presented, incorporating information on internal vibrational motion from ab initio cluster calculations using the ONIOM approach implemented in GAUSSIAN03. The method is tested by comparing model H-atom ADPs with reference values, largely from neutron diffraction experiments, for a variety of molecular crystals: benzene, 1-methyluracil, α-glycine, xylitol and 2-methyl-4-nitroaniline. The results are impressive and, as the method is based on widely available software, and is in principle widely applicable, it offers considerable promise in future charge-density studies of molecular crystals.


Sign in / Sign up

Export Citation Format

Share Document