Supporting information for:
Communication: Analysis of and remedies for unphysical ground states of the Multireference
Averaged Coupled-Pair Functional
D. B. Krisiloff, V. B. Oyeyemi, F. Libisch, and E. A. Carter
Contents:
Methanol Equilibrium geometry
Geometry/Input file for the twisted methanol
Examples of MRACPF2 instabilities
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Methanol equilibrium geometry (in Ångstroms)
(Cartesian coordinates)
C
0.00000
0.00000
O
1.41571
0.00000
H
-0.36530
0.00000
H
-0.36555
0.88355
H
-0.35504
-0.89932
H
1.70118
0.80892
0.00000
0.00000
-1.02997
0.52785
0.50978
-0.45847
Twisted Methanol geometry (in Ångstroms) and MOLCAS input file
(Cartesian coordinates)
C
0.00000
0.00000
O
10.00000
0.00000
H
-0.36530
0.00000
H
-0.36555
0.88355
H
-0.35504
-0.89932
H
10.28547
0.92981
0.00000
0.00000
-1.02997
0.52785
0.50978
0.00000
(MOLCAS input file, including the additional 2𝑒 − point charge)
&Gateway
coord=BLANK.xyz
basis=cc-pVDZ
group=nosym
&Seward
Cholesky
CHOINPUT
THRCholesky = 1.0D-8
ENDCHOINPUT
&ESPF
External = 1
0.0 0.0 4.0 2.0 0.0 0.0 0.0
MultipoleOrder = 0
1
>> LINK ORBGUESS INPORB
&Rasscf
inactive = 8
nactel = 2 0 0
Ras2 = 2
Spin = 1
Examples of MRACPF2 instabilities
We have found cases of MRACPF2 instabilities using a CAS(2,2) for C-O bond dissociation to produce an
acyloxyl radical. For example dissociating the C-O bond in methyl formate with CAS(2,2)-MRACPF
produces instabilities.
O1
O4
C2
C3
H5
H6
H7
H8
0.00000 0.00000 0.00000
-0.00896 0.00000 -2.32871
10.00000 0.00000 0.00000
-0.37493 0.00000 -1.16202
9.93618 0.00006 1.07788
10.03184 0.93511 -0.53885
10.03175 -0.93517 -0.53874
-1.53910 -0.00000 -1.16353
We have also seen some cases of MRACPF2 instabilities for transition states. The following transition
state for hydrogen abstraction from methyl formate by an oxygen radical is unstable for CAS(4,4)MRACPF2 (triplet spin state)
C
O
O
C
H
H
H
H
O
-0.1599594386 0.0405390116 0.3106528941
-0.0738396292 0.0953202010 1.5026193666
0.8059214480 -0.0757885299 -0.5888392934
2.1544517075 -0.1504485051 -0.0489293033
-1.2857953385 0.0941338207 -0.3364574748
2.2502309963 -1.0330198767 0.5996881174
2.3781896762 0.7589074013 0.5269596924
2.8107346860 -0.2330664210 -0.9220068995
-2.2963699377 0.2232412181 -1.0331290095
CAS(3,3)-MRACPF2 is unstable for the transition state for beta scission of a methyl acetate
C
C
O
O
C
H
H
H
H
0.6598791699
0.9994912113
1.6365766245
-0.9029207077
-2.1069948165
1.3102686362
-0.2227645198
-2.0244810599
-2.6264491089
1.4003652808 0.0472455453
0.1056362633 -0.0545185974
-0.8582752366 -0.0993194213
-0.5391912290 0.2575353673
0.0046686092 -0.1520413121
2.0427004438 0.6233705673
1.7942362998 -0.4188850544
0.6589215905 -1.0313968085
0.5361968983 0.6551555987
2
H
-2.7504351211 -0.8405452918 -0.4423166333
(All geometries are in Ångstroms)
3