Performance, Precision, Technical

In some cases we found that the accuracy of the ADF numerical integration grid fell somewhat below expectation, sometimes resulting in a warning or error abort 'INACCURATE ETA INTEGRALS' or 'BAD ETA INTEGRALS'. To solve this, a few technical parameters in the grid generator have been adjusted. For a given accuracy parameter (the input key Integration) this will produce more points (roughly 10%) than was the case in ADF1999, with a corresponding increase in computing time but yielding more stability, robustness and reliability.

ADF calculations with large numbers of point charges ( most of them far away from the real molecule) were very slow, due to a very large number of (mostly redundant) numerical integration grid points. This has been cleaned up, resulting in a significant gain in speed for such calculations.