New algorithms for an individually selecting MR-CI program Original Research Article

In the present work we discuss the main features of new algorithms to do individually-selecting MR-CI calculations. Employing a new program package we are able to perform calculations including more than two million selected configuration state functions (CSFs) as a matter of routine. A test calculation on the C6 molecule including about 2.3 mill. selected CSFs takes about 54 minutes on a PentiumPro for one iteration within the Davidson procedure. This enables one to study more complicated and larger systems with a higher accuracy than before.