<div dir="ltr">Dear all<div>      Hello everyone, I am currently learning the usage of the external potential, see “<a href="https://www.cp2k.org/events:2016_summer_school:qmmm?s[]=external&s[]=potential">https://www.cp2k.org/events:2016_summer_school:qmmm?s[]=external&s[]=potential</a>” for a related introduction. Among them, I don't understand what the “PARAMETERS A B”  mean? What kind of electric field is this？</div><div><p><img alt="QQ图片20210624124428.png" data-iml="228899.78000009432" width="534px" height="169px" src="cid:571415b0-3e07-44ec-b732-8f4b1912d31a"><br></p><p><br></p></div></div>