Quantum Simulation: How Does It Help Single Molecules Survive Different Temperatures, Stabilize Unique Nanostructure?

In a new study, an international team of researchers revealed the universal stabilization mechanism of a single-standing molecule, which can be employed in the rational design and building of three-dimensional molecular devices at surfaces.

According to a Phys.org report, nanoscale machinery has many different functions. These include delivery of the drug, memory storage, and single-atom transistor, among others.

Nevertheless, such machinery needs to be assembled at the nanoscale, a substantial challenge for researchers.

The ultimate goal for nanotechnology engineers is to construct functional machinery, part-by-part at the nanoscale.

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(Photo: SLAC National Accelerator Laboratory on Wikimedia Commons)
Simulation of a 3-D structure reconstruction from the diffraction of a single molecule

Objects That Can Be Grabbed and Assembled

As specified in the paper published in Science Advances, objects can be grabbed and, later on, assembled in the macroscopic world.

It is no longer impossible for single molecules to be grabbed, although their quantum nature makes their reaction to manipulation unpredictable, restricting the ability to pull together one by one.

This project is now nearer its materialization because of an international initiative led by the Research Centre Jülich of the Helmholtz society in Germany, including researchers from the Department of Chemistry at the University of Warwick.

Use of a Scanning Probe Microscope

Essentially, the SPM or scanning probe microscope has brought the molecular-scale fabrication's vision closer to reality. It offers the ability to rearrange atoms and molecules on surfaces, thus enabling the development of metastable structures that do not form instinctively.

Through using an SPM, Dr. Christian Wagner, together with his team, successfully interacted with a single-standing molecule known as perylene-tetracarboxylic dianhydride or PTCDA. This is detailed in the National Library of Medicine on a surface to examine the thermal stability and the temperature at which the molecule would stop stable and drop back into its natural condition where it is adsorbing flat on the surface.

Quantum chemical calculations carried out in collaboration with the Department of Chemistry at the University of Warwick's Dr. Reinhard Maurer were able to show that the delicate stability of the molecule is stemming from the competition of two neutralizing quantum forces, identified as the long-range attraction from the surface and the short-range restoring force that arises from the anchor point between the surface and molecule.

Quantum Chemical Simulation

Commenting on the research finding, the Department of Chemistry at the University of Warwick's Dr. Reinhard Maurer said the balance of interactions, keeping the molecule from falling over is quite delicate, not to mention a true challenge for the quantum chemical simulation approaches.

On top of learning about the fundamental mechanisms that stabilize such unique nanostructures, the project helped in assessing and improving the capabilities of such methods.

From the Peter Grünberg Institute for Quantum Nanoscience (PGI-3) at Research Centre Jülich, Dr. Wagner also said that to develop technological use of the captivating quantum properties of individual molecules; there is a need to search for the right balance. More so, they need to be immobilized on a surface, although minus fixing them quite strongly; otherwise, they would lose such properties.

Standing molecules are perfect in that respect, as a similar Nanowerk report specified. To gauge how stable the molecules exactly are, the researchers said in their study; they had to stand them up over and over using a sharp metal needle. They also timed how long the molecules survived at different temperatures.

Now that the interactions giving rise to stable standing molecules have been identified, future studies can develop better molecules and molecule-surface associates to tune such quantum interactions.

This can help enhance stability and the temperature at which molecules can be swapped into standing arrays towards workable situations. This increases the prospect of nanofabrication of machinery at the nanoscale.

Related information about the quantum mechanics of materials and molecules is shown on CogX's YouTube video below:

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