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

TUNCUR codes are aimed at a coherent calculation of both equilibrated structures and electronic properties of a sample and 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 that perform HF SCF semi-empirical 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 current-voltage characteristic of the tunneling gap.