Effects of Isotope Substitution on Local Heating and Inelastic current in Hydrogen Molecular Junctions

Using first principle approaches, we investigate the effects of isotope substitution on the inelastic features in the hydrogen molecular junction. We observe thatlocal heating and inelastic current have significant isotope-substitution effects. Due to the contact characters, the energies of excited molecular vibrationsare inverse proportional to the square root of the mass. The heavier the molecule, the smaller the onset bias. In the $H_{2}$ and $D_{2}$ junctions, the heavier molecule has a smaller magnitude of electron-vibration interaction. Consequently, there is a crossing in the local temperature around $80 K$. In the HD junction, the electron-vibration interaction is enhanced by asymmetric distribution in mass. It leads to the largest discontinuity in the differential conductance and the most prominent heating in the HD junction. We predict that the junction instability is relevant to isotope substitution. The HD junction has the smallest breakdown voltage compared with the $H_{2}$ and $D_{2}$ junction

Seebeck coefficient of thermoelectric moleculat junction: First-principles calculations

A first-principles approach is presented for the thermoelectricity in molecular junctions formed by a single molecule contact. The study investigates the Seebeck coefficient considering the source-drain electrodes with distinct temperatures and chemical potentials in a three-terminal geometry junction. We compare the Seebeck coefficient in the amino-substituted and unsubstituted butanethiol junction and observe interesting thermoelectric properties in the amino-substituted junction. Due to the novel states around the Fermi levels introduced by the amino-substitution, the Seebeck coefficient could be easily modulated by using gate voltages and biases. When the temperature in one of the electrodes is fixed, the Seebeck coefficient varies significantly with the temperature in the other electrode, and such dependence could be modulated by varying the gate voltages. As the biases increase, richer features in the Seebeck coefficient are observed, which are closely related to the transmission functions in the vicinity of the left and right Fermi levels.Comment: 4 pages; 2 figure

The relationships between corruption and pollution on corruption regimes

Previous studies have focused mainly on the effect of corruption on pollution. The results of these studies show an inverted U-shaped relationship between economic growth and pollution. In addition, some researchers have suggested that corruption plays an important role in determining pollution. This study proposes the hypothesis of a nonlinear long-run relationship between pollution and corruption. The goal of the study is to investigate the threshold cointegration effect of pollution on corruption using panel data for 62 countries over the period from 1997 to 2004. The results show that the effect of the Corruption Perceptions Index (CPI) on pollution is insignificant in low-corruption regimes. This implies that corruption does not slow down environmental pollution in countries with low corruption. The impact of the CPI on environmental pollution is also insignificant in high-corruption regimes. This result implies that corruption has no adverse impact on environmental pollution in countries with high corruption.Corruption, Pollution, Threshold, Error-Correction Model