  Recent modeling of Neutron Star Interior Composition Explorer(NICER)
observations of the millisecond pulsar PSR J0030+0451 suggests that the
magnetic field of the pulsar is non-dipolar. We construct a magnetic field
configuration where foot points of the open field lines closely resemble the
hotspot configuration from NICER observations. Using this magnetic field as
input, we perform force-free simulations of the magnetosphere of PSR
J0030+0451, showing the three-dimensional structure of its plasma-filled
magnetosphere. Making simple and physically motivated assumptions about the
emitting regions, we are able to construct the multi-wavelength lightcurves
that qualitatively agree with the corresponding observations. The agreement
suggests that multipole magnetic structures are the key to modeling this type
of pulsars, and can be used to constrain the magnetic inclination angle and the
location of radio emission.
