Posted by Coen de Graaf on May 12, 2011 at 10:04:44:

Hi,

I encountered a problem with the parallel execution of the module numerical_gradient in MOLCAS 7.6. When the number of nodes available to this module is not an exact multiple of the number of displacements to be calculated the code gets stuck and does not escape from the numerical_gradient anymore. It seems to me that the job is waiting for the results of those nodes on which a fake process was started. For instance, using 8 nodes to calculate 12 displacements. In the first step 8 displacements are done in parallel, then 4 nodes get a 'real' calculation and on the other four a 'fake' process is started. Now molcas gets never beyond this step. This does not happen in molcas 7.4!! A pragmatic solution is to choose the number of nodes in function of the displacements but this is not very practical.

A second question concerns the ISC calculation with CASPT2. The manual is contradictory on the possibility of doing such calculation. In section 6.7.7 it is explicitly states that numerical gradients in the ISC search are not implemented, while in the input description of slapaf under the keyword ISCOptimization, the caspt2 option is mentioned.

All the best,

Coen

- Re: parallel execution numerical gradients
**Steven Vancoillie***14:17:26 5/26/11*(0)