AFM/STM simulation Tool


	Nano Times
	Nt_STM The classic STM simulation software package designed for STM experimentalists Nt_STM calculates the electrical current through any given nanometrical system (microscope tip + sample + surface) and reproduces the results of a real STM. It gives current or topographic mode results as well as I(v) or I(z) curves, just like in your experiment. (see these movies for basic demonstration or these case studies ) Building a system … Comparing results Nt_STM calculates all interactions between the atoms and provides results accuracy and similarity with the experiments' results. The simulation engine available today is based on Dr. Jorge Iribas Cerda's "Green" code. More engines are to be added soon. The nanometrical system is represented by the Extended Hückel Theory (EHT). More precise theoretical chemistry programs can be integrated toNt_STM for specific simulations. Simply draw your system, design your surface and tip, adjust your EHT quantum parameters, launch the simulation and compare the simulated results with those of your STM !!

	Nt_AFM The AFM simulation software package designed for AFM experimentalists Motivated by the need to aid in the interpretation of experimental Atomic Force Microscopy (AFM) images, this software was developed to self-consistently calculate the interaction between a tip and surface, and then use this interaction in running a virtual AFM machine that simulates a real experimental device. The Nt_AFM simulation engine is based on King's College Dr. Lev Kantorovich Sci-Fi and vAFM original codes. As far as we are aware, this is the most advanced AFM simulating tool commercially available today. The software can be run in three regimes: as a semi-classical simulation tool (known separately as the SciFi code) as a virtual AFM machine (vAFM), in which case a 3D force field is assumed to be prepared separately (preprocessed); in this case the SciFi part of the software is not activated; as a combination of the two. In this case the vAFM machine is used as an engine for moving the tip. At each tip position the atoms in the microscopic part are allowed to relax to mechanical equilibrium using the specified interactions between them, and then the force on the tip is calculated. This is performed by the SciFi part of the software. The tip force is then fed into the vAFM part to process, and, by advancing difference equations governing electronics, a new position of the tip is calculated that is fed back into the SciFi part. Integrated in a unique interface, Nt_AFM allows for a precise, step-by-step monitoring of the system's (surface+tip+sample) deformations. Nt_AFM : take your AFM image to a new level of comprehension
	Nt_GREEN The Green [1,2] simulation engine (by Dr. Jorge Iribas Cerda) is a software package designed for theoreticians No great interface here, but handy features for experimented users! Features included: work either with standard unit cells (diagonalization) or with complex structures involving blocks of different dimensionality via Green's functions (e.g. the STM); use either a semi-empirical Hamiltonian (EHT or Tight Binding) or the abinitio DFT based SIESTA framework; a large amount of tools to calculate/analyze/view the electronic structure: PDOS, COOPs, charge densities, projections onto AOs, MOs, etc.; transport properties in out of equilibrium conditions: elastic transmission in nanodevices (e.g. STM, nanotubes, graphene, etc.); calculation of vibrational modes/phonons; inelastic currents: electron-vibrational mode coupling, IETS; spin-orbit (LS) output… Ask for your free evaluation copy of the Green software packaged by Nanotimes. [1] Cerda, J. and Van Hove, M. A. and Sautet, P. and Salmeron, M., Efficient method for the simulation of STM images. I. Generalized Green-function formalism, Phys. Rev. B, 1997, 56 (24), 15885. [2] Cerda, J. and Yoon, A. and Van Hove, M. A. and Sautet, P. and Salmeron, M. and Somorjai, G. A., Efficient method for the simulation of STM images. II. Application to clean Rh(111) and Rh(111)+c(4×2)-2S, Phys. Rev. B, 1997, 56 (24), 15900.