1. The problem statement, all variables and given/known data 1. For a simple cubic lattice with a lattice constant of a, the energy band can be expressed as:E = Acos(kxa)cos(kya)cos(kza) + B. (a) Suppose the effective mass for the electron at conduction band is m* = -ħ2/2a2, find A. 2. Relevant equations 3. The attempt at a solution I know the effective mass equation and how the effective mass tensor is calculated, but I can't really see how does the effective mass appear to be as indicated(m* = -ħ2/2a2). Thanks!