Evaluation of General and Tailor Made Force Fields via X-ray Thermal Diffuse Scattering Using Molecular Dynamics and Monte Carlo Simulations of Crystalline Aspirin

2018 ◽  
Vol 14 (4) ◽  
pp. 2165-2179 ◽  
Author(s):  
Eric J. Chan ◽  
Marcus A. Neumann
Keyword(s):  
Molecular Dynamics ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Diffuse Scattering ◽  
Force Fields ◽  
Thermal Diffuse Scattering ◽  
X Ray ◽  
Thermal Diffuse

On the use of molecular dynamics simulation to calculate X-ray thermal diffuse scattering from molecular crystals

2015 ◽  
Vol 48 (5) ◽  
pp. 1420-1428 ◽  
Author(s):  
E. J. Chan
Keyword(s):  
Molecular Dynamics ◽  
Diffuse Scattering ◽  
Molecular Crystals ◽  
Dynamics Simulation ◽  
Thermal Diffuse Scattering ◽  
X Ray ◽  
Interaction Terms ◽  
Functional Forms ◽  
Dynamics Simulations ◽  
Thermal Diffuse

The use of molecular dynamics simulations to calculate the thermal diffuse scattering from X-ray diffraction experiments on molecular crystals is described, using the crystal structure of aspirin form I as an example system. Parameter settings that do not affect the actual simulation are varied in order to examine the effect on the final calculated diffraction pattern, and thus roughly determine a range for general settings that might be used in further experiments targeted at tailoring parameters associated with the functional forms for dispersion interaction terms commonly used in molecular simulation force fields. The proposed method is compared with that of the more widely accepted Monte Carlo technique, and possible advantages and drawbacks for the use of either method are discussed.

Diffraction Pattern Caused by X-Ray Thermal Diffuse Scattering in Absorbing Perfect Crystal

1988 ◽  
Vol 57 (2) ◽  
pp. 524-534 ◽  
Author(s):  
Yasuji Kashiwase ◽  
Masahiro Mori ◽  
Motokazu Kogiso ◽  
Masayuki Minoura ◽  
Satoshi Sasaki
Keyword(s):  
Diffraction Pattern ◽  
Diffuse Scattering ◽  
Perfect Crystal ◽  
Thermal Diffuse Scattering ◽  
X Ray ◽  
Thermal Diffuse

Practical Aspects of Removing the Effects of Elastic and Thermal Diffuse Scattering from Spectroscopic Data for Single Crystals

2014 ◽  
Vol 20 (4) ◽  
pp. 1078-1089 ◽  
Author(s):  
Nathan R. Lugg ◽  
Melissa J. Neish ◽  
Scott D. Findlay ◽  
Leslie J. Allen
Keyword(s):  
Factor Analysis ◽  
Energy Loss ◽  
Single Crystals ◽  
Electron Energy ◽  
Diffuse Scattering ◽  
Energy Dispersive ◽  
Thermal Diffuse Scattering ◽  
X Ray ◽  
Electron Energy Loss ◽  
Thermal Diffuse

AbstractA method to remove the effects of elastic and thermal diffuse scattering (TDS) of the incident electron probe from electron energy-loss and energy-dispersive X-ray spectroscopy data for atomically resolved spectrum images of single crystals of known thickness is presented. By calculating the distribution of the probe within a specimen of known structure, it is possible to deconvolve the channeling of the probe and TDS from experimental data by reformulating the inelastic cross-section as an inverse problem. In electron energy-loss spectroscopy this allows valid comparisons with first principles fine-structure calculations to be made. In energy-dispersive X-ray spectroscopy, direct compositional analyses such as ζ-factor and Cliff–Lorimer k-factor analysis can be performed without the complications of channeling and TDS. We explore in detail how this method can be incorporated into existing multislice programs, and demonstrate practical considerations in implementing this method using a simulated test specimen. We show the importance of taking into account the scattering of the probe in k-factor analysis in a zone axis orientation. The applicability and limitations of the method are discussed.

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