From owner-chemistry@ccl.net Fri May  1 11:02:01 2015
From: "Igors Mihailovs igors.mihailovs0::gmail.com" <owner-chemistry _ server.ccl.net>
To: CCL
Subject: CCL: Spin contamination increased by annihilation of the first-order contaminant
Message-Id: <-51337-150501110125-32146-YbeXmPHP3SSRrtVJ5+XgZA _ server.ccl.net>
X-Original-From: Igors Mihailovs <igors.mihailovs0]|[gmail.com>
Content-Type: multipart/alternative; boundary=001a11c33f0213daf10515067cb1
Date: Fri, 1 May 2015 18:00:58 +0300
MIME-Version: 1.0


Sent to CCL by: Igors Mihailovs [igors.mihailovs0_._gmail.com]
--001a11c33f0213daf10515067cb1
Content-Type: text/plain; charset=UTF-8

Dear all,

I was quite surprised when, during stability analysis of my wavefunction
and subsequent reoptimization of it in unrestricted space, the spin
contamination was not descreased by removal of the first-order contaminant:


  SCF Done:  E(RHF) =  -2277.17663511     A.U. after    1 cycles
            NFock=  1  Conv=0.39D-08     -V/T= 2.0012
 [..]
 The wavefunction has an RHF -> UHF instability.
 The two search directions are symmetric.
 [..]
 SCF Done:  E(UHF) =  -2277.19705082     a.u. after   42 cycles
            Convg  =    0.4967D-05                   164 Fock formations.
              S**2 =  2.1080                  -V/T =  2.0009
 <Sx>= 0.0000 <Sy>= 0.0000 <Sz>= 0.0000 <S**2>= 2.1080 S= 1.0356
 <L.S>= 0.000000000000E+00
 Annihilation of the first spin contaminant:
 S**2 before annihilation     2.1080,   after     8.9661


Is there some way to interpret this result?

Looking forward to Your help,
Igors Mihailovs (engineer)
Institute of Solid State Physics
University of Latvia

--001a11c33f0213daf10515067cb1
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div><div>Dear all,<br><br></div>I was quite surprised whe=
n, during stability analysis of my wavefunction and subsequent reoptimizati=
on of it in unrestricted space, the spin contamination was not descreased b=
y removal of the first-order contaminant:<br><br><br>=C2=A0 SCF Done:=C2=A0=
 E(RHF) =3D=C2=A0 -2277.17663511=C2=A0=C2=A0=C2=A0=C2=A0 A.U. after=C2=A0=
=C2=A0=C2=A0 1 cycles
<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 NFoc=
k=3D=C2=A0 1=C2=A0 Conv=3D0.39D-08=C2=A0=C2=A0=C2=A0=C2=A0 -V/T=3D 2.0012
<br>=C2=A0[..]
<br>=C2=A0The wavefunction has an RHF -&gt; UHF instability.
<br>=C2=A0The two search directions are symmetric.
<br>=C2=A0[..]
<br>=C2=A0SCF Done:=C2=A0 E(UHF) =3D=C2=A0 -2277.19705082=C2=A0=C2=A0=C2=A0=
=C2=A0 a.u. after=C2=A0=C2=A0 42 cycles
<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 Conv=
g=C2=A0 =3D=C2=A0=C2=A0=C2=A0 0.4967D-05=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
 164 Fock formations.
<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0 S**2 =3D=C2=A0 2.1080=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 -V/T =3D=C2=A0=
 2.0009
<br>=C2=A0&lt;Sx&gt;=3D 0.0000 &lt;Sy&gt;=3D 0.0000 &lt;Sz&gt;=3D 0.0000 &l=
t;S**2&gt;=3D 2.1080 S=3D 1.0356
<br>=C2=A0&lt;L.S&gt;=3D 0.000000000000E+00
<br>=C2=A0Annihilation of the first spin contaminant:
<br>=C2=A0S**2 before annihilation=C2=A0=C2=A0=C2=A0=C2=A0 2.1080,=C2=A0=C2=
=A0 after=C2=A0=C2=A0=C2=A0=C2=A0 8.9661
<br>=C2=A0<br><br></div>Is there some way to interpret this result?<br><div=
><br clear=3D"all"><div><div><div><div class=3D"gmail_signature"><div dir=
=3D"ltr">Looking forward to Your help,<br><div>Igors Mihailovs (engineer)<b=
r></div><div>Institute of Solid State Physics<br></div><div>University of L=
atvia<br></div><div><br></div></div></div></div>
</div></div></div></div>

--001a11c33f0213daf10515067cb1--