Generalized divide-conquer method

A generalized divide-conquer (GDC) method, in which a cluster is taken into account as the core region instead of a single atom in the DC method, is available by the following option:

     scf.EigenvalueSolver       GDC

The core region is automatically determined so that the computational efficiency can be maximized and this scheme can be more efficient than the conventional DC method for low dimensional systems, while the details are not shown here. The total number of truncated clusters is reduced as a result of the clustered core region which is the reason for the efficiency. As well as the DC method, the accuracy and efficiency are controlled by the two keywords: 'orderN.HoppingRanges' and 'orderN.NumHoppings'.