Efficiency and accuracy of the elongation method as applied to the electronic structures of large systems

Current state of development of the elongation method originally proposed by Imamura is presented. Recent progress in methodology, including geometry optimization and employment of the fast multiple method, is highlighted. The accuracy and efficiency of the elongation method as compared to exact canonical Hartree-Fock and Kohn-Sham approaches are discussed. Potential applications are illustrated by wide range of calculations for model systems. The elongation calculations are demonstrated to be much more efficient compared to the conventional ones with high accuracy maintained. The elongation CPU time is shown by the model calculations as linear or sub-linear scaling for quasi-one-dimensional systems. Future work of development into post-Hartree-Fock methodologies are pointed out. (C) 2006 Wiley Periodicals, Inc.