Experimental dynamic electron densities of multipole models at different temperatures
Swastik Mondal1, Siriyara Jagannatha Prathapa, Sander van Smaalen
1Laboratory of Crystallography, University of Bayreuth, 95440 Bayreuth, Germany.
Summary
Accurate dynamic electron density (ED) maps were computed using fast Fourier transforms. These maps, free of series-termination effects, reveal that dynamic EDs closely resemble static EDs, especially at bond critical points, even at higher temperatures.
Area of Science:
- Crystallography
- Quantum Chemistry
- Materials Science
Background:
- Accurate electron density (ED) determination is crucial for understanding chemical bonding and molecular properties.
- Dynamic EDs, accounting for atomic vibrations, offer a more realistic representation than static EDs.
- Previous methods often struggled with series-termination effects and accurately modeling dynamic EDs.
Purpose of the Study:
- To compute dynamic electron densities using an accurate method.
- To analyze the topological properties of dynamic EDs and compare them with static EDs.
- To investigate the temperature dependence of dynamic electron densities.
Main Methods:
- Computation of dynamic EDs via inverse Fourier transform of structure factors using fast Fourier transform (FFT).
- Development of multipole (MP) models for α-glycine and D,L-serine.
- Refinement of models against X-ray diffraction data and analysis of topological features like bond critical points (BCPs).
Main Results:
- Successfully generated series-termination-effect-free dynamic ED maps.
- Dynamic EDs showed expected topological properties, with maxima near atomic positions and at BCPs.
- Dynamic EDs were similar to static EDs, particularly at low temperatures and in low-density regions like hydrogen bonds.
- Differences between static and dynamic EDs increased with temperature, potentially indicating temperature-dependent properties.
Conclusions:
- Dynamic electron density calculations using FFT are reliable for determining topological properties.
- Dynamic EDs provide a more accurate picture of electron distribution, especially concerning atomic vibrations.
- The temperature dependence of dynamic EDs offers insights into molecular and solid-state properties, including chemical stability and reactivity.
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