IETS and quantum interference: propensity rules in the presence of an interference feature

Destructive quantum interference in single molecule electronics is an intriguing phe- nomenon; however, distinguishing quantum interference effects from generically low transmission is not trivial. In this paper, we discuss how quantum interference ef- fects in the transmission lead to either low current or a particular line shape in current-voltage curves, depending on the position of the interference feature. Sec- ondly, we consider how inelastic electron tunneling spectroscopy can be used to probe the presence of an interference feature by identifying vibrational modes that are se- lectively suppressed when quantum interference effects dominate. That is, we expand the understanding of propensity rules in inelastic electron tunneling spectroscopy to molecules with destructive quantum interference.Comment: 19 pages, 6 figure

Single-molecule Electronics: Cooling Individual Vibrational Modes by the Tunneling Current

Electronic devices composed of single molecules constitute the ultimate limit in the continued downscaling of electronic components. A key challenge for single-molecule electronics is to control the temperature of these junctions. Controlling heating and cooling effects in individual vibrational modes, can in principle, be utilized to increase stability of single-molecule junctions under bias, to pump energy into particular vibrational modes to perform current-induced reactions or to increase the resolution in inelastic electron tunneling spectroscopy by controlling the life-times of phonons in a molecule by suppressing absorption and external dissipation processes. Under bias the current and the molecule exchange energy, which typically results in heating of the molecule. However, the opposite process is also possible, where energy is extracted from the molecule by the tunneling current. Designing a molecular 'heat sink' where a particular vibrational mode funnels heat out of the molecule and into the leads would be very desirable. It is even possible to imagine how the vibrational energy of the other vibrational modes could be funneled into the 'cooling mode', given the right molecular design. Previous efforts to understand heating and cooling mechanisms in single molecule junctions, have primarily been concerned with small models, where it is unclear which molecular systems they correspond to. In this paper, our focus is on suppressing heating and obtaining current-induced cooling in certain vibrational modes. Strategies for cooling vibrational modes in single-molecule junctions are presented, together with atomistic calculations based on those strategies. Cooling and reduced heating are observed for two different cooling schemes in calculations of atomistic single-molecule junctions.Comment: 18 pages, 6 figure

Administration Economics Programme in Nigerian Universities: Problem and Suggestion

The article discussed the problems facing the administration of Economics programme in Nigerian higher institutions. Secondary data was used to support the points raised in the article. The secondary data were sourced from print material and online publication by recognized institutions and individual author. The article identified inadequate funding of Economics programme, inadequate Economics lecturers, and shortage of infrastructural facilities in Economics, institutional corruption, unstable academic calendar, poor staff development and brain-drain as the challenges facing the administration of Economics programme in the Nigerian higher institutions. To solve these challenges, hence, this article recommends: that the government should increase the funding of Economics programme, employ more lecturers, provide more infrastructural facilities in the Economics department, ensure stable academic calendar and fight all institutional corruption in the university system

First Principle Calculations to Predict the Preferred Crystal and Structural Parameter of Indium Phosphate

The structural and electronic properties and phase transition under pressure of Indium phosphide in Zinc-blende, Rock salt, and wurtzite structure were studied using the first principle calculations based on the density functional theory by means of the pseudo-potential plane-waves method. The calculation was performed within the Generalised Gradient Approximations (GGA) within Perdew-Burke and Ernzerhof (PBE) exchange-correlation functional. On the basis of the Murnaghan equation of state, the transition pressure between the Zinc-Blende to RockSalt phases, Zinc-blende to Wurtzite, and RockSalt to Wurtzite was investigated

Structural and Electronic Properties of Gallium Phosphate Semiconductor in Wurtzite Rock-Salt and Zinc-Blende

First principle method was used to study the structural and electronic properties of Gallium Phosphate in Wurtzite, zinc blende and rock salt using the molecular dynamics density functional theory implemented on the Quantum Espresso software. For this work the choice of the pseudo-potential is the GGA, scf calculation was used for zinc blende and rock salt to test the convergence of kinetic energy cut-off, lattice parameter, number of k-point with respect to 1mRy energy and 0.5kbar pressure. The same was repeated in wurtzite but vc-relax was used, all the plots obtained for the three structure converges towards the set threshold, the plot of band structure and density of state reveals that rock salt is a metal due to absence of band gap while other are semi-conductors with an indirect band gap, a plot of energy versus enthalpy shows that there’s a transition from zinc blende to rock salt with about 18.73% decrease in volume from zinc blende to rock salt and this occur at a pressure of 29.07GPa, it is noteworthy that Gallium Phosphate was found to be more stable in zinc blende

Structural and Electronic Properties of Gallium Phosphate Semiconductor in Wurtzite Rock-Salt and Zinc-Blende

First principle method was used to study the structural and electronic properties of Gallium Phosphate in Wurtzite, zinc blende and rock salt using the molecular dynamics density functional theory implemented on the Quantum Espresso software. For this work the choice of the pseudo-potential is the GGA, scf calculation was used for zinc blende and rock salt to test the convergence of kinetic energy cut-off, lattice parameter, number of k-point with respect to 1mRy energy and 0.5kbar pressure. The same was repeated in wurtzite but vc-relax was used, all the plots obtained for the three structure converges towards the set threshold, the plot of band structure and density of state reveals that rock salt is a metal due to absence of band gap while other are semi-conductors with an indirect band gap, a plot of energy versus enthalpy shows that there’s a transition from zinc blende to rock salt with about 18.73% decrease in volume from zinc blende to rock salt and this occur at a pressure of 29.07GPa, it is noteworthy that Gallium Phosphate was found to be more stable in zinc blende

First Principle Calculations to Predict the Preferred Crystal and Structural Parameter of Indium Phosphate

The structural and electronic properties and phase transition under pressure of Indium phosphide in Zinc-blende, Rock salt, and wurtzite structure were studied using the first principle calculations based on the density functional theory by means of the pseudo-potential plane-waves method. The calculation was performed within the Generalised Gradient Approximations (GGA) within Perdew-Burke and Ernzerhof (PBE) exchange-correlation functional. On the basis of the Murnaghan equation of state, the transition pressure between the Zinc-Blende to RockSalt phases, Zinc-blende to Wurtzite, and RockSalt to Wurtzite was investigated

Office of the Registrar in Nigerian Public Universities: Problems and Suggestions

The article discussed the problems facing the office of the Registrar in Nigerian public universities. Secondary data was used to support the points raised in the article. This article obtains the secondary data from print material and online publication by recognized institutions and individual author. Some problems facing the office of Registrar of Nigerian public universities include; inadequate funding of the office of Registrar, inadequate staff/over-staffed, inadequate infrastructural facilities, inadequate working materials, poor capacity development of staff in the Registrar’s office. To solve these challenges, this article recommends: that the school administrators should increase the funding of the office of Registrar, provide adequate infrastructural facilities, employment of more staff/deployment of staff out, provision of adequate working materials and effective staff development programme for staff in office of the Registrar

Group Theoretical Approach To Squeezed States Using Generalized Bose Operators

Generalized, k-boson Holstein-Primakoff realizations of SU(2) and SU(1,1) are introduced In terms of generalized bose operators. The corresponding group theoretical coherent states are studied with respect to their squeezing properties relative to k-boson dynamical variables