Fragment molecular orbital calculations under periodic boundary condition

The periodic boundary condition (PBC) is incorporated in the fragment molecular orbital (FMO) method to appropriately describe systems with aqueous solutions. We present benchmark calculations for ( H 2 O ) 64 and show that this PBC-FMO method can eliminate artificial surface effects. An application to molecular dynamics simulation for liquid water is also shown, and calculated radial distribution functions are in reasonable agreement with those obtained from experiments. It is thus confirmed that the present PBC-FMO method is useful for ab initio simulations in aqueous solution.