Related Experiment Video
Updated: May 16, 2026
13:56
Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations
Published on: October 12, 2019
Isomerization dynamics of a buckled nanobeam
Peter Collins1, Gregory S Ezra, Stephen Wiggins
1School of Mathematics, University of Bristol, Bristol BS8 1TW, United Kingdom.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|December 11, 2012
Summary
We studied silicon nanobeam dynamics under compression, revealing non-ergodic behavior and oscillatory decay. This suggests a rate constant for nanobeam isomerization does not exist in this model.
Area of Science:
- Solid Mechanics
- Nonlinear Dynamics
- Computational Physics
Background:
- Nanobeams are crucial in micro/nanoelectromechanical systems.
- Understanding their dynamic stability under stress is essential for device design.
- Compressive stress can induce complex behaviors like buckling and mode instabilities.
Purpose of the Study:
- To analyze the dynamics of a compressed nanobeam using a two-mode truncation of the Euler-Bernoulli beam equation.
- To investigate the analogy between nanobeam "isomerization" (transition between buckled states) and chemical isomerization reactions.
- To explore the influence of different potential energy surface saddle types on the beam's dynamic behavior.
Main Methods:
- Employed a two-mode truncation of the Euler-Bernoulli beam equation for nanobeam dynamics.
- Utilized concepts from chemical isomerization reaction theory to model beam transitions.
- Analyzed potential energy surfaces with index one and index two saddles.
- Computed reactive fluxes, mean gap times, and phase space volumes.
Main Results:
- The nanobeam model exhibits non-ergodic dynamics, with isomerizing trajectories sweeping less phase space than the reactant density of states.
- Gap time distributions showed "pulses" of trajectories, not a smooth decay.
- Reactive flux correlation functions displayed oscillatory decay, lacking a plateau.
Conclusions:
- The dynamics of the two-mode nanobeam model under compression are highly non-ergodic.
- A classical rate constant for isomerization does not appear to exist for this system under the studied conditions.
- The analogy with chemical isomerization provides a useful framework for understanding complex mechanical transitions.
Related Concept Videos
02:11Conformations of Cyclohexane
Cyclohexane does not exist in a planar form due to the high angle and torsional strain it would experience in the planar structure. Instead, it adopts non-planar chair and boat conformations.
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
01:15Deformation of a Beam under Transverse Loading
Understanding beam deflection, particularly for indeterminate beams with overhanging segments and multiple concentrated loads, is crucial for ensuring structural integrity and functionality. The process begins with constructing an accurate free-body diagram, which helps identify the forces and moments acting on the beam. This diagram is vital for visualizing how bending moments vary along the beam's length, influencing its curvature.
The insights from the bending moment diagram extend to...
The insights from the bending moment diagram extend to...
02:02Chair Conformation of Cyclohexane
The chair conformation is the most stable form of cyclohexane due to the absence of angle and torsional strain. The absence of angle strain is a result of cyclohexane’s bond angle being very close to the ideal tetrahedral bond angle of 109.5° in its chair conformer. Similarly, the torsional strain is also absent owing to the perfectly staggered arrangement of bonds.
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this staggered...
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this staggered...
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
01:15Unsymmetric Bending - Angle of Neutral Axis
Unsymmetrical bending occurs when a structural member is subjected to bending moments in a plane that does not align with the member's principal axes. This scenario typically arises in beams and other structural components when loads are applied at non-ideal angles, introducing complexities in stress analysis.
When a bending moment is applied at an angle θ concerning the vertical axis of a symmetrical member, it can be resolved into components along the member's principal centroidal axes. The...
When a bending moment is applied at an angle θ concerning the vertical axis of a symmetrical member, it can be resolved into components along the member's principal centroidal axes. The...
01:17Beams with Unsymmetric Loadings
Analyzing a supported beam under unsymmetrical loadings is essential in structural engineering to understand how beams respond to varied force distributions. This analysis involves calculating the deflection and identifying points where the slope of the beam is zero, which are crucial for ensuring structural stability and functionality.
The first moment-area theorem determines the slope at any point on the beam. This theorem indicates that the change in slope between two points on a beam...
The first moment-area theorem determines the slope at any point on the beam. This theorem indicates that the change in slope between two points on a beam...