This technique has recently been used by other authors [8] to prepare tips in situ for low-temperature STM. In this paper, we show experimental results of the JC and JOC phenomena for gold that are analyzed simultaneously. We study the most

probable configurations before the formation and breaking of nanocontacts with pyramidal form obtained from MD simulations emulating the process of mechanical annealing. As found earlier [5], the contacts can be classified into monomer, dimer and double contact. In order to correlate with the experimentally obtained conductance values, we calculated the conductance of these structures using first-principles quantum transport models. Methods We have used an STM, where the tip and sample were two gold electrodes with 99.999% purity. The experiments were done at 4.2 K and cryogenic vacuum atmosphere. In order

to obtain the conductance of selleck products the contacts, the electrical current was measured while applying a 100-mV constant bias voltage between the gold structures. Figure 1A shows Selleck Pictilisib traces of conductance in a gold nanocontact, measured in units of G 0 during the process of formation (red) and rupture (green). Insets show some click here snapshots from our molecular dynamics simulations. These correspond to the initial structure (top figure) and the final structures before breaking (bottom right) and just after contact formation (bottom left). Figure 1B is a zoomed area around 1G 0 of Figure 1A, where the phenomena of JC and JOC can be clearly observed. In order to quantify the jump occurring in these two processes, we define

two conductance values for JC (G a , G b ) and two values for JOC (G c , G d ). These values correspond to the conductance values before and after the jump. Thymidylate synthase We have performed thousands of indentations and recorded the values of these points. Representing G b vs G a for the JC case and G d vs G c for JOC, we can obtain a colour density plot as shown in Figure 1C for JC and in Figure 1D for JOC. Lighter colours are less probable values than darker colours. Figure 1 How to build a density plot. (A) On the top left-hand side, we show a typical trace of conductance of gold at 4 K during the process of breaking (red) and forming (green) a contact. (B) The top right-hand side is a zoom near 1G 0 to define the values before and after the JC, G a and G b , and JOC, G c and G d . (C, D) The bottom figures show colour density plots where dark colours represent those values of conductance that appear more frequently (left for JC and right for JOC). To emulate the movement of the STM and simulate the tip and surface that are annealed mechanically, we used MD simulations with embedded atom potentials. Density function theory (DFT)-based calculations are performed to obtain the electronic transport in the simulated structures [9].