2010-08-25
 - YOU HAVE OUTCOMMENTED THE NON-LOCAL CONTRIBUTIONS TO THE SECOND-ORDER DERIVATIVE OF THE ENERGY !!!!!
2010-08-11
 - Bug 1: error in the eigenvalue term of the SternheimerOperator
 - Bug 2: density on the fine grid constructed from the non-mixed coarse density
2010-04-08
 - Density is now calculated as a complex quantity
2010-03-29
 - Implementation for periodic system initiated
 - Changed default solver method from `gmres` to `cg` in ScipyLinearSolver