MPS overlaps with specified determinants

[ghb24]

Hi Block2Devs,
I was wondering whether it was possible for Block2 to compute the overlap with specified determinants? I can see in the docs that it can find all overlaps with determinants/CSFs greater than a specific threshold, but is it possible to find e.g. the amplitudes on all double excitations of a reference determinant for tailored-CCSD? Potentially also with a threshold imposed?
Many thanks in advance

[hczhai]

Thanks for your interest in using block2.

This can be done using the given_dets argument in DMRGDriver.get_csf_coefficients, see https://block2.readthedocs.io/en/latest/api/pyblock2.html#pyblock2.driver.core.DMRGDriver.get_csf_coefficients. Detailed explanation can be found in #70 (reply in thread). When working in the SZ mode, you need given_dets=['2ba0ba', '0ab2ba'] (for example).

Minimal block2 version that supports this feature is 0.5.3rc5. You can install this version (or any later version) using

pip install block2==0.5.3rc5 --extra-index-url=https://block-hczhai.github.io/block2-preview/pypi/

[ghb24]

Fantastic - many thanks for the quick response!