Abstract
Molecular electronics saw its birth with the idea to build electronic circuitry with single molecules as individual components. Even though commercial applications are still modest, it has served an important part in the study of fundamental physics at the scale of single atoms and molecules. It is now a routine procedure in many research groups around the world to connect a single molecule between two metallic leads. What is unknown is the nature of this coupling between the molecule and the leads. We have demonstrated recently (Tewari, 2018, Ph.D. Thesis) our new setup based on a scanning tunneling microscope, which can be used to controllably manipulate single molecules and atomic chains. In this article, we will present the extension of our molecular dynamic simulator attached to this system for the manipulation of single molecules in real time using a graphics processing unit (GPU). This will not only aid in controlled lift-off of single molecules, but will also provide details about changes in the molecular conformations during the manipulation. This information could serve as important input for theoretical models and for bridging the gap between the theory and experiments.
Highlights
Researchers have been interested in understanding electronic transport through single molecules for several decades
Quantum interference [2,3], thermo-electricity [4,5] and molecular spintronics [6,7] are some of the many exotic phenomena that one can study in single molecules
The atomic scale structure of the contacts and the details of the binding of the molecule to these leads have to be known. These details include knowledge of the binding sites, the nature of the bond, the conformational state of the molecule, the bond angles, etc. These are important parameters to know because our understanding of electronic transport through single molecules depends on the output of various computational models like density functional theory (DFT), non-equilibrium Greens function (NEGF) theory, etc., which require these parameters as inputs
Summary
Researchers have been interested in understanding electronic transport through single molecules for several decades. These details include knowledge of the binding sites, the nature of the bond, the conformational state of the molecule, the bond angles, etc These are important parameters to know because our understanding of electronic transport through single molecules depends on the output of various computational models like density functional theory (DFT), non-equilibrium Greens function (NEGF) theory, etc., which require these parameters as inputs. Single planar molecules connected between the STM tip and sample while keeping the atomic structure of surface intact were studied using I(t) and I(s)measurements reported by Haiss et al [20,21] in ambient conditions These measurements require doing statistics on the current jumps that are detected as molecules spontaneously make and break contact between the tip and the surface when the STM tip is brought close to the flat metallic surface (with a low coverage of molecules). We will discuss the challenges involved in making this simulation real time and present the solutions we provided, explaining the assumptions and improvements we made
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