Large-scale FMO-MP3 calculations on the surface proteins of influenza virus, hemagglutinin (HA) and neuraminidase (NA)

A complex consisting of hemagglutinin (HA) trimer and two Fab-fragments (Protein Data Bank-id: 1KEN) was calculated at the FMO-MP3/6-31G level on the Earth Simulator (ES2) as a massively parallel-vector computer. The numbers of total atoms, residues and basis functions were as many as 36 160, 2351 and 20 1276, respectively, and this large-scale job was completed only in 5.8 h with 1024 processors. Analyses of inter-fragment interaction energy (IFIE) revealed asymmetric interactions among monomeric HA domains and the significance of electron correlation effects. A complex formed between neuraminidase (NA) and oseltamivir was calculated as well.