From KIRALJ#* at *#olimp.irb.hr Wed Nov 2 12:27:13 1994 Received: from olimp.irb.hr for KIRALJ /at\olimp.irb.hr by www.ccl.net (8.6.9/930601.1506) id LAA13266; Wed, 2 Nov 1994 11:48:06 -0500 Received: from olimp.irb.hr by olimp.irb.hr (MX V4.1 VAX) with SMTP; Wed, 02 Nov 1994 17:47:26 MET-DST Date: Wed, 2 Nov 1994 17:47:24 +0200 (IST) From: RUDOLF KIRALJ Subject: hydrogen atom in MOPAC To: CHEMISTRY \\at// ccl.net Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Hi Netters! The most trivial problem in calculating atomic structures is H atom. So the MOPAC 6.00 calculations gave 11.906 eV (MNDO), 11.396 eV (AM1) and 13.073 eV (PM3) for hydrogen atom ionization potential. There is no difference in usign spin restricted or unrestricted hamiltonian. The experimental value is 13.595 eV. The differences between the experiment and calculations (roughly 1.7/2.2/0.5 for MNDO/AM1/PM3) are two or three orders of magnitude greater than experimental error. If in this case one have such difference, what about all other systems? Can somebody give appropriate explanation? Rudolf _________ kiralj -A_T- olimp.irb.hr