  Solar eruptive activities could occur in weak magnetic field environments and
over large spatial scales, especially relevant to eruptions involving
intermediate or quiescent solar filaments. To handle the large scales, we
implement and apply a flux rope embedding method using regularized Biot-Savart
laws in the spherical coordinate system. Combined with a potential field source
surface model and a magneto-frictional method, a nonlinear force-free field
comprising a flux rope embedded in a potential field is constructed. Using the
combined nonlinear force-free field as the initial condition, we then perform a
zero-$\beta$ data-constrained magnetohydrodynamic (MHD) simulation for an M8.7
flare at 03:38 UT on 2012 January 23. The MHD model reproduces the eruption
process, flare ribbon evolution (represented by the quasi-separatrix layer
evolution) and kinematics of the flux rope. This approach could potentially
model global-scale eruptions from weak field regions.
