Shifted-force Coulomb potential

Figure 9 shows the Coulomb potential, the shifted-force Coulomb potential (Eq. [31]), the shielded Coulomb potential (Eq. [32]), and the shielded shifted-force Coulomb potential (Eq. [33]) calculated for interaction between two hydrogen atoms with a charge = + e. ... 

Figure 9 Electrostatic interaction energy between two hydrogen atoms represented by the shifted-force Coulomb and shielded Coulomb potentials.

Just as in the shifted-force method, the taper method replaces a strict cutoff radius by a cutoff region in which the interactions are smoothly tapered to zero. This is done by multiplying the Coulomb potential from r = Ator = B... 

Each simulation extended to about 15000 time-steps after a pre-equilibration of approximately the same length. Ewald summation in tabulated form was used for the Coulomb interactions, and the shifted-force method (e.g., Allen and Tildesley 1987) was used for the non-Coulomb parts of the BJH potential. All technical details of the simulations are described in detail elsewhere (Kalinichev and Heinzinger 1992, 1995 Kalinichev 1993). 

Now, from the way pp and np phase shift analyses are conducted, it is clear that a potential that fits the np phase shifts well, will automatically fit the pp phase shifts well, qfier the small but important corrections for Coulomb and charge-dependence have been applied (similarly to what is done in the phase shift analysis). A good example for this is the Bonn potential that has originally been fit to np [15] and has a f /datum of 1.9 for the world np data (cf. Table 1). Now, when the Coulomb force is included and the S scattering length is adjusted to its pp value, then the world pp data are reproduced with a f /datum of also 1.9 (instead of 641 [31], which is a meaningless number). 

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