TY  - RPRT
TI  - Nonorthogonal density-matrix perturbation theory.
AU  - Anders M N Niklasson
AU  - Valéry Weber
AU  - Matt Challacombe
PY  - 2005
DO  - 10.1063/1.1944725
UR  - https://pubmed.ncbi.nlm.nih.gov/16095346/
ID  - 16095346
ER  -