Method for calculating the electronic structures of large molecules; helical polymers.

We present a self-consistent one-electron scheme for calculating ground-state properties of large systems with complex boundaries. It is based on linear muffin-tin orbitals (LMTO’s) and the density functional formalism in its local approximation. A multiple-κ LMTO basis set is used. No shape approximations, neither for the potential nor for the charge density, are made. Outside the spheres the charge density is fitted to a series of atom-centered Hankel functions and the two- and three-center integrals used for the overlap and Hamiltonian matrices, as well as for the charge density fit, are performed analytically. Inside the spheres the non-muffin-tin part of the charge density is treated by spherical-harmonics expansions. It is shown how the method can be applied to helical polymers. Test calculations on the N2 molecule are reported. [ABSTRACT FROM AUTHOR]