Hello,I'm physics student.I'm from Vietnam and my English is not very good. I was wondering if anyone could help me out with a question : what are scattered states and bound states ? I'm interested in "Temperature-dependent Coulomb interation in hydrogenic systems". In this topic,the effective pair potential is defined as afunction of the two-particle radial distribution function (rdf). When particles have charges of opposite sign,their rdf can be considered as a sum of two terms : the contributions from scattered states and bound states . I 've looked up those in many books,but I haven't found the answer.Please help me.Thanks.