https://doi.org/10.1063/1.4885056 this is paper I’m referring.
Can anyone tell how to get <R^2>, <alpha^2> and frobenius norm in QChem ?
https://doi.org/10.1063/1.4885056 this is paper I’m referring.
According to the paper, <alpha^2> is just the radius of gyration (alpha = x,y,z) of the ground-state wave function. That’s probably negligibly different from its Hartree-Fock counterpart, in which case you can get it from the Cartesian quadrupole tensor, which involves expectation values , , and and is printed at the end of the Q-Chem job, and for the individual orbitals (and density) by setting PRINT_RADII_GYRE = TRUE. There are also CAP-specific onset keywords in the Q-Chem documentation, e.g., here:
https://manual.q-chem.com/latest/sub_cc_cs_cap.html
For the W matrix, I’m not sure. Please read the documentation.
The expectation values of <X^2>, <Y^2>, and <Z^2>, which together measure a size of electronic density, are printed as part of properties output. You need to request calculation of properties:
For the CCSD values, set cc_ref_prop = true
For the EOM-CC values, set
cc_eom_prop = true
I also recommend this review to learn more about CAP methods in Q-Chem:
T.-C. Jagau, K.B. Bravaya, and A.I. Krylov, Extending quantum chemistry of bound states to electronic resonances, Ann. Rev. Phys. Chem. 68 , 525 – 553 (2017).