<div>Motivated by our resent detection of the ambipolar-diffusion (AD) scale for cloud turbulence (Tang, Li & Lee 2018), we developed Scorpio for molecular cloud simulations. The AD scale, 0.4 pc, is compared to cores, which are largely simulated by single-fluid ideal or non-ideal magnetohydrodynamics (MHD) in the literature. <br></div><div><br></div><div>Scorpio is a grid-based two-fluid non-ideal MHD code based on the finite-volume method. Based on the Godunov method, the conservation parts of the fluid are solved by approximate Riemann solvers combined with a piecewise linear reconstruction (PLM) at the cell interfaces and constrained transport (CT) for preserving the solenoidal constraint of magnetic fields. Additionally, for the source terms, the Poisson equation for the self-gravity is solved using Fast Fourier Transformation method (FFT). The ion-neutral collisional term, AD, is integrated using a second-order semi-implicit method, TR-BDF2 algorithm, to deal with the stiffness.</div><div><br></div><div>Besides demonstrating the accuracy by conventional ideal or two-fluid MHD tests, here we also present applications on magnetic braking and two-fluid turbulence.</div>
[Poster PDF File]