BHandHLYP method

In Fig. 17 we show the histogram of interaction-induced mean polarizability for all methods. With the notable exception of the BHandHLYP method the interaction property aint(H20)2 is negative for all ab initio methods and positive for the DFT... 

Mata et al have determined the dynamic polarizability and Cauchy moments of liquid water by using a sequential molecular dynamics(MD)/ quantum mechanical (QM) approach. The MD simulations are based on a polarizable model of liquid water while the QM calculations on the TDDFT and EOM-CCSD methods. For the water molecule alone, the SOS/TDDFT method using the BHandHLYP functional closely reproduces the experimental value of a(ffl), provided a vibrational correction is assumed. Then, when considering one water molecule embedded in 100 water molecules represented by point charges, a(co) decreases by about 4%. This decrease is slightly reduced when the QM part contains 2 water molecules but no further effects are observed when enlarging the QM part to 3 or 4 water molecules. These molecular properties have then been employed to simulate the real and imaginary parts of the dielectric constant of liquid water. 

In the absence of experimental data for SE anih it could be of interest to carry out calculations relying on a reference theoretical method to predict excitation energies. EOM-CCSD gas-phase excitation energies for the MOx syn- and flwh-isomers are also reported in Table 4. The EOM-CCSD results indicate that DFT, in particular, the B3LYP exchange-correlation functional, underestimates SE anti- However, the difference between EOM-CCSD (2,258 cm = 0.28 eV) and BHandHLYP (1,726 cm = 0.21 eV) calculations is quite small (0.07 eV). 

Vertical excitation energies (AE, eV) of transient negative ion (TNI) of DNA/RNA bases calculated using TD-BSLYP/fr-SIG and TD-BHandHLYP/6-31G methods and their comparison with available experimental values ... 

In Table 5 we give all monomer and dimer value used in the analysis of the results. The H2O monomer (M) values pertain to the molecular geometry of the moiety in the dimer. The per-monomer (PM) values are simply defined as PM = AD/2 that is a(H20)2/2 for the polarizability and y(H20)2/2 for the hyperpolarizability. The properties of interest are the interaction mean (hyper) polarizabilities obtained by the formula AD — AX — XD (see above). A first and valuable observation here is the strong disagreement of ab initio and DFT methods on the (hyper)polarizability of the water dimer. Such behavior for the DFT methods has been noted and analyzed early enough [127]. We must emphasize at this point the essential difference of the BHandH and BHandHLYP DFT methods. Both seem to be very close to the ab initio ones and quite distinct from the other DFT approaches. 

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