Hans Bernhard "Berny" Schlegel is a German-born computational and theoretical chemist, and distinguished professor at Wayne State University. He is a highly cited chemist, with a Thomson Reuters H-Index of 116 and citations of over 218,000 as of 2020. He is a professor of chemistry at the Wayne State University and co-author of the computational chemistry software, Gaussian. The "Berny optimization" as implemented in Gaussian is named after him. His group also created the Electronic Structure Perl Toolkit (ESPT).