### Gradient of potential surface

Posted:

**16 Jan 2020, 15:31**I am interested in trajectory calculations and would therefore like to access the gradient of the potential. According to the user manual I can request for the numerical derivative of the potential using *CCGR and .NUMGD. In the attached file (

Note that for reasons of computational efficiency, I would like to map/fit the potential first before I start running the trajectory calculations. I could obtain the gradient myself by making some displacements and evaluating the potential energy differences. However, I expect that an evaluation in one DALTON run is more efficient and more accurate.

How can I get access to the gradient at a specified configuration using the CCSD level of accuracy? I am interested in the ground state.

UPDATE:

Using *NMDDRV I am able to get the gradient at the HF level. It seems that I cannot get the gradient at the CCSD level because 1DHAM001 integrals are not read( ).

) I used these keywords but did not get any output for the gradient.Note that for reasons of computational efficiency, I would like to map/fit the potential first before I start running the trajectory calculations. I could obtain the gradient myself by making some displacements and evaluating the potential energy differences. However, I expect that an evaluation in one DALTON run is more efficient and more accurate.

How can I get access to the gradient at a specified configuration using the CCSD level of accuracy? I am interested in the ground state.

UPDATE:

Using *NMDDRV I am able to get the gradient at the HF level. It seems that I cannot get the gradient at the CCSD level because 1DHAM001 integrals are not read( ).