Journal of Chemical Physics, Vol.107, No.24, 10823-10826, 1997
Frequency dependent equation-of-motion coupled cluster hyperpolarizabilities: Resolution of the discrepancy between theory and experiment for HF?
We formulate and apply the EOM-CC method to determine, recursively, any order and any process frequency dependent hyperpolarizability. Combining the theory with systematically chosen n-aug-cc-pVXZ bases, we attempt to converge to the basis set Limit. Our best "relaxed" result is -9.8 +/- 0.5 a.u. for beta(SHG) compared to an experimental value of -11.0+/-1 a.u. and 720+/-40 a.u. for gamma dc-SHG compared to 840+/-120 a.u. If orbital relaxation could be neglected, the results are -10.2+/-0.5 a.u. and 730+/-40 a.u., falling within the error bars. (C) 1997 American Institute of Physics.