TUNCUR: Sequential codes for semiempirical quantum chemical calculations of tunneling current

TUNCUR codes are aimed at a self-consistent calculation of both equilibrated structures and electronic properties of a sample and scanning tunneling microscopy (STM) tip altogether with the tunneling current between them in the framework of the same computational scheme. Both objects are modeled by atomic clusters. Quantum chemical calculations in TUNCUR codes are provided by sequential programs, CLUSTER-Z1 and CLUSTER-Z2, which perform Hartree-Fock self-consistent field semiempirical calculations in the valence sp- and spd-basis, respectively. TUNCUR consists of three main blocks that provide calculations of STM recordings in two modes of operation as well as computing local density of states. All calculations are performed over a grid of variable parameters. There are two additional blocks for calculations of both the current Z-dependence and volt-ampere characteristic of the tunneling gap. (C) 2004 Wiley Periodicals, Inc.