B..2 Features that were new in MOLPRO2000

Relative to version 98.1, there are the following principal changes and additions:

1. There was a fundamental error in the derivation of the spin-restricted open-shell coupled-cluster equations in J. Chem. Phys. 99, 5129 (1993) that is also reflected in the RCCSD code in Molpro version 98.1 and earlier. This error has now been corrected, and an erratum has been published in J. Chem. Phys. 112, 3106 (2000). Fortunately, the numerical implications of the error were small, and it is not anticipated that any computed properties will have been significantly in error.

2. There was a programming error in the transformation of gradients from cartesian to internal coordinates, which in some cases resulted in slow convergence of geometry optimizations. The error is now fixed.

3. Vibrational frequencies formerly by default used average atomic masses, rather than those of the most common isotopes, which is now the default behaviour.

4. MCSCF second derivatives (author Riccardo Tarroni) added (preliminary version, only without symmetry). Frequency and geometry optimization programs are modified so that they can use the analytic hessian.

5. New internally contracted multireference second-order perturbation theory code (author Paolo Celani) through command RS2C, as described in P. Celani and H.-J. Werner, J. Chem. Phys. 112, 5546 (2000).

6. EOM-CCSD for excited states (author Tatiana Korona).

7. QCISD dipole moments as true analytical energy derivatives (author Guntram Rauhut).

8. Linear scaling (CPU and memory) LMP2 as described by G. Hetzer, P. Pulay, and H.-J. Werner, Chem. Phys. Lett. 290, 143 (1998).
   M. Schütz, G. Hetzer, and H.-J. Werner, J. Chem. Phys. 111, 5691 (1999).

9. Improved handling of basis and geometry records. 98.1 and 99.1 dump files can be restarted, but in case of problems with restarting old files, add RESTART,NOGEOM immediately after the file card. Also, if there are unjustified messages coming up in very large cases about "ORBITALS CORRESPOND TO DIFFERENT GEOMETRY" try ORBITAL,record,NOCHECK. (This can happen for cases with more than 100 atoms, since the old version was limited to 100).

10. Reorganization and generalization of basis input. Increased basis library.

11. Counterpoise geometry optimizations.

12. Improved running procedures for MPP machines. Parallel direct scf and scf gradients are working. These features are only available with the MPP module, which is not yet being distributed.

13. Important bugfixes for DFT grids, CCSD with paging, finite field calculations without core orbitals, spin-orbit coupling.

14. Many other internal changes.

As an additional service to the Molpro community, an electronic mailing list has been set up to provide a forum for open discussion on all aspects of installing and using Molpro. The mailing list is intended as the primary means of disseminating hints and tips on how to use Molpro effectively. It is not a means of raising queries directly with the authors of the program. For clearly demonstrable program errors, reports should continue to be sent to molpro-support@tc.bham.ac.uk; however, `how-to' questions sent there will merely be redirected to this mailing list.

In order to subscribe to the list, send mail to majordomo@tc.bham.ac.uk containing the text subscribe molpro-user; for help, send mail containing the text help.

Messages can be sent to the list (molpro-user@tc.bham.ac.uk) and viewed in the archive at http://www.tc.bham.ac.uk/molpro/molpro-user/archive irrespective of whether or not you subscribe to the list. Experienced Molpro users are encouraged to post responses to queries raised. Please do contribute to make this resource mutually useful.