From schw0531@compszrz.zrz.tu-berlin.de Tue Feb 2 11:00:31 1993 Date: Tue, 2 Feb 93 10:00:31 +0100 From: Prof. Dr. Helmut Schwarz Message-Id: <9302020900.AA12793@compszrz.zrz.tu-berlin.de> To: CHEMISTRY@ccl.net, WILLSD@CONRAD.APPSTATE.EDU Subject: Re: anion structure? the handling of anions at the standard ab initio level is extremely difficult. The results are very sensitive to the basis set and method of the inclusion of the correlation energy. In my opinion the minimal basis giving reasonable results is 6-31++G**, however larger polarized basis sets with d- and f- functions are needed to obtain more accurate answers about thermochemistry of anions. Jan Hrusak