An effective core potential (ECP) with power >= 3

[kousuke-nakano]

First of all, we thank you for developing this fantastic library. We are now doing DFT calculations with semi-local effective core potentials (ECPs) using CP2K [https://github.com/cp2k/cp2k], where integrals are evaluated using the libgrpp library. As far as we understand, libgrpp does not support an ECP with power >= 3, which is right now preventing us from using CP2K for a research project. We would like to know if you plan to extend the parameterization of pseudopotentials to an ECP with power > = 3.

typedef struct {
int L; // spatial angular momentum of the PP operator
int J; // total angular momentum of the PP operator
int num_primitives; // number of Gaussian primitives in the PP expansion
int *powers; // powers ’n’ for each PP primitive <--- this
double *coeffs; // coefficients of the PP expansion double
*alpha; // exponents of the PP expansion
} libgrpp_potential_t;

Best regards.

[aoleynichenko]

Dear Kosuke Nakano,

such integrals are currently not implemented in libgrpp. However, it seems to be not very problematic to implement integrals for such a parametrization. In principle I can do it in near future (not in July, however, due to other immediate tasks...) Maybe you know some other well-established software implementing them? (in order to validate the code).
I'll let you know if I implement integrals for n >= 3.

Best wishes,
Alexander

[kousuke-nakano]

Dear @aoleynichenko Thank you very much. We look forward to the implementation. We will definitely acknowledge you and cite your paper. Best regards. Kosuke Nakano

[kousuke-nakano]

Dear @aoleynichenko, I wonder if you have any updates on this issue. It would be helpful for our on-going project if CP2K could compute n>3. By the way, I'm sorry I did not reply to your question.

Maybe you know some other well-established software implementing them? (in order to validate the code).

Yes, PySCF supports n>=3. So, once you implement n >=3 in your library, I can test it by comparing CP2K and PySCF.