Re: [AMBER] CYM residue problem(MCPB)

From: Jason Swails <>
Date: Thu, 17 Oct 2013 11:49:08 -0400

On Thu, Oct 17, 2013 at 11:29 AM, houcemeddine <> wrote:

> Hi,
> I try to parametrize a metal cluster containing 1 CYM residue and 3 others
> HID. Until the steps of generating the input com files , all is working
> perfectly, except when I run gaussian it always give the error: The
> combination of multiplicity 1 and 219 electrons is impossible.

I believe this problem is unrelated to your sidechain.bcl file. Your metal
cluster has an odd number of electrons, yet in your Gaussian input file you
claim that the multiplicity is 1. A multiplicity of 1 indicates that there
are no spin-unpaired electrons. If you have an odd number of electrons,
though, at least one of your spins must be unpaired, meaning that your
multiplicity must be an even number (2 means 1 electron is unpaired, 4
means 3 electrons are unpaired, etc.). It is important that you figure out
what your spin multiplicity is and then adjust the Gaussian input file
accordingly. Another thing to note is that you cannot use a restricted
method (e.g., RHF) to compute a wavefunction or electron density. You need
to use some method that can handle open-shell systems (e.g., ROHF or UHF).


Jason M. Swails
Rutgers University
Postdoctoral Researcher
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Received on Thu Oct 17 2013 - 09:00:03 PDT
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