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Influencia de las distorsiones de baja simetría en el transporte de electrones a través de cadenas de átomos
Vihar P Georgiev1, John E McGrady
1Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom.
Journal of the American Chemical Society
|July 14, 2011
Resumen
En electrónica molecular, el transporte de electrones en cadenas atómicas metálicas no está sorprendentemente dominado por orbitales pi deslocalizados. En cambio, las órbitas sigma de mayor energía conducen corriente, incluso con distorsiones estructurales.
Área de la Ciencia:
- La electrónica molecular es la electrónica molecular.
- La química cuántica es una química cuántica.
- Ciencia de los materiales ciencia de los materiales.
Sus antecedentes:
- A menudo se asume que la deslocalización de los orbitales moleculares es crucial para el flujo de corriente en la electrónica molecular.
- La simetría estructural, al igual que las longitudes de enlace uniformes, suele estar vinculada a la deslocalización orbital.
- Estudios previos propusieron un marco de π deslocalizado como la vía de conducción primaria en las cadenas de Cr{3}{dpa}{4}{NCS}{2}.
Objetivo del estudio:
- Investigar la relación entre la deslocalización orbital, la simetría estructural y el transporte de electrones en cadenas extendidas de átomos metálicos.
- Desafiar el supuesto convencional que vincula la deslocalización y la conductividad.
- Para identificar las rutas orbitales dominantes para el transporte de electrones en Cr
Principales métodos:
- Cálculos de la teoría funcional de la densidad (DFT).
- Formalismo de las funciones de Green (NEGF) de no equilibrio.
- Análisis de las distorsiones de baja simetría en las cadenas de átomos de metal Cr.
Principales resultados:
- Las distorsiones de baja simetría reducen la efectividad de los canales π, pero son irrelevantes para el transporte de baja parcialidad, ya que están por debajo del nivel de Fermi.
- Los orbitales σ más altos, no los orbitales π, son la vía dominante para el transporte de electrones.
- La conductividad aumenta ligeramente a medida que el canal σ (n) se desplaza más cerca del nivel de Fermi debido a las distorsiones.
Conclusiones:
- La relación entre la estructura y la función en las cadenas metálicas es sutil y contraintuitiva.
- La simetría orbital y los niveles de energía, en lugar de solo la deslocalización, dictan la conductividad.
- Los hallazgos tienen implicaciones significativas para la interpretación de los datos experimentales de las técnicas de microscopía de sonda de barrido en la electrónica molecular.
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