The quantum geometric tensor Q_μν = g_μν + i/2·Ω_μν encodes the geometry of Bloch states over the Brillouin zone. The real part g_μν is the quantum metric (relates to wavepacket spread), the imaginary part Ω is the Berry curvature (Hall conductivity). Here for a 2-band model H(k) = d(k)·σ.