This bug was my fault. Fixed files are attached and in the repository for buck/coul/long and born/coul/long. When I introduced coulomb tabling to these pair styles, r was not being computed for the non-coulomb part of this calculation. Unlike most other pair styles, these pair styles need r for the non-coulomb part of the calculation. Putting in "r = sqrt(rsq)" on line 153 of buck/coul/long solves the problem. Thanks for pointing out this bug --- and sorry for the hassle.
Incidentally, another work-around is turning off coulomb tabling by using "pair_modify table 0". These pair styles will run considerably faster with tabling on, so on is the default.
pair_born_coul_long.cpp (17.4 KB)
pair_buck_coul_long.cpp (16.1 KB)