Per-Olov Löwdin

Per-Olov Löwdin (October 28, 1916 in Uppsala, Sweden – October 6, 2000) was a Swedish physicist, professor at the University of Uppsala from 1960 to 1983, and in parallel at the University of Florida until 1993. A former graduate student under Ivar Waller, Löwdin formulated in 1950 the symmetric orthogonalization scheme for molecular orbital calculations. This scheme is the basis of the zero-differential overlap (ZDO) approximation used in semiem... more

Per-Olov Löwdin (October 28, 1916 in Uppsala, Sweden – October 6, 2000) was a Swedish physicist, professor at the University of Uppsala from 1960 to 1983, and in parallel at the University of Florida until 1993. A former graduate student under Ivar Waller, Löwdin formulated in 1950 the symmetric orthogonalization scheme for molecular orbital calculations. This scheme is the basis of the zero-differential overlap (ZDO) approximation used in semiempirical theories. He is also credited with the use of fat symbols for matrices, making easy the derivation of several theorems of quantum mechanics. The famous 'Löwdin pairing theorem' used in ROHF, UHF and RES-GVB theories is not his. According to himself, George G. Hall and King made the formal proposition after an informal suggestion by Löwdin. His partitioning technique for quantum chemistry problems is best appreciated through the series of 14 papers on perturbation theory published between 1963 and 1971. He was also a very active teacher... less