INDO calculation in Caussian

From: jz7|at|duke.edu
Subject: INDO calculation in Caussian
Date: Wed, 1 Dec 2004 19:26:08 -0500 (EST)

Dear all,
 I am trying to do single point calculation for a molecule (actually it
 includes three small molecules and no bond between them, so the non-bonded
 interaction keeps them close). It has no charge and all the electrons are
 paired. So I set charge to 0 and multiplicity to 1. The wierd thing is
 that when I use HF method, the calculation works, but i I change to INDO,
 it complains about that "Specified charge and multiplicity are
 impossible". And the following is my command line:
 For HF:
 #HF/3-21G iop(5/33=3)
 For INDO
 #INDO iop(5/33=3)
 I don't understand why HF work, INDO doesn't. All the input structural
 information is the same.
 Thanks for the help!
 Best,
 Jeny