Evaluation of self-energy matrix for electrode based on real-space pseudopotential method

Evaluation of self-energy matrix for electrode is one of the bottleneck parts of the first-principles transport calculation. Over the past years, several methods have been developed to reduce the computational cost, however calculation is still slow especially when the real-space pseudopotential method is employed because the Hamiltonian matrix of the unit cell becomes very large.
We present a method to evaluate the self-energy matrix especially for real-space pseudopotential method. The method combines the partitioning technique [1] with singular value decomposition, which transforms the Hamiltonian matrix of a unit cell into the maximally contracted form. Because of the simplicity of the method, typical methods such as quick decimation method [2] and semi-analytical method [3] can be used for the contracted Hamiltonian without large modification. We applied this method for several examples and validated the accuracy and efficiency of the method.

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[3] S. Sanvito, C. J. Lambert, J. H. Jefferson, and A. M. Bratkovsky, Phys. Rev. B 59, 11936 (1999)