The Kubo transformed velocity auto-correlation function in liquid para-hydrogen as obtained from TGMD in comparison with the RPMD result (Ref. 34). ρ=, and N = 108 molecules. The black line depicts the first approach, the explicit computation of the Kubo transform from Eq. (44); the second approach, termed “easy” Kubo, Eq. (56), is shown in red.
in liquid para-hydrogen as obtained from Eq. (56) for various system sizes at the to state points, ρ = , and respectively , . The results obtained with Eq. (44) are almost identical, as shown in Fig. 1, and are no longer included. The dash-dotted line depicts the window function (60) used to estimate the diffusion constant.
Quantum spectra of the standard velocity auto-correlation function for various system sizes in comparison with the RPMD result (Ref. 34) Top: ρ = , ; bottom: , . The spectra were converted according to Eq. (12). The crosses show the spectrum after attenuation with Eq. (60), as used for the estimation of the diffusion constant.
Diffusion constant as a function of system size. The lines show the linear fit D(N −1/3) = D(∞) − αN −1/3.
Parameters of the Gaussians [cf. Eq. (57)] used to approximate the SG potential.
Calculated self-diffusion constant of liquid para-H2.
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