content_image/305044.jpg content_image/305050.jpg
<img src='content_image/305044.jpg'>

completeness by fitting our data to the empirically determined expression g$_{E}$ cut (0) = g ∞ (0)+ $_{a/}$√$_{E}$$_{cut}$$_{+}$$_{b/E}$$_{cut}$$_{, where}$ a and b are fitting parameters. The residual finite-size error in g (0) is less than about 1%. 

The electron-positron contact PCF is plotted in Fig. 3. Adapting the fitting form of Ref. [6] slightly, we represent our contact PCF data by 

<img src='content_image/305050.jpg'>

where a$_{3}$$_{/}$$_{2}$ = − 1 . 56672, a$_{2}$ = 4 . 16983, a$_{7}$$_{/}$$_{3}$ = − 3 . 579, and a$_{8}$$_{/}$$_{3}$ = 0 . 836389. Equation (4) satisfies both the high- density (random phase approximation) [12] and low-density (Ps $^{−}$) limiting behavior [11]. 

The extra interaction reduces the contact PCF at all the densities we have studied, by about 8% at r$_{s}$ = 1, rising to about 15% at r$_{s}$ = 8. Our electron-positron PCF results are in reasonably good agreement with the many-body-theory results of [13, 14, 21, 22], but are in strong disagreement with the QMC results [16, 17], which give much smaller 

