The Unitary Group Adapted State-Specific Multi-Reference Perturbation Theory (UGA-SSMRPT2) developed by Mukherjee et al. [J. Comput. Chem. 36, 670 (2015)] has successfully realized the goal of studying bond dissociation in a numerically stable, spin-preserving, and size-consistent manner. We explore and analyze here the efficacy of the UGA-SSMRPT2 theory in the description of the avoided crossings and interlacings between a manifold of potential energy curves for states belonging to the same space-spin symmetry. Three different aspects of UGA-SSMRPT2 have been studied: (a) We introduce and develop the most rigorous version of UGA-SSMRPT2 that emerges from the rigorous version of UGA-SSMRCC utilizing a linearly independent virtual manifold; we call this the “projection” version of UGA-SSMRPT2 (UGA-SSMRPT2 scheme P). We compare and contrast this approach with our earlier formulation that used extra sufficiency conditions via amplitude equations (UGA-SSMRPT2 scheme A). (b) We present the results for a variety of electronic states of a set of molecules, which display the striking accuracy of both the two versions of UGA-SSMRPT2 with respect to three different situations involving weakly avoided crossings, moderate/strongly avoided crossings, and interlacing in a manifold of potential energy curves (PECs) of the same symmetry. Accuracy of our results has been benchmarked against IC-MRCISD + Q. (c) For weakly avoided crossing between states displaying differently charged sectors around the crossing region, the insufficient inclusion of state-specific orbital relaxation and the absence of dynamic correlation induced by orbital relaxation in the first order wavefunction for a second order perturbative theory lead to an artifact of double crossing between the pair of PECs.

1.
D. I.
Lyakh
,
M.
Musiał
,
V. F.
Lotrich
, and
R. J.
Bartlett
,
Chem. Rev.
112
,
182
(
2012
).
2.
P. G.
Szalay
,
T.
Müller
,
G.
Gidofalvi
,
H.
Lischka
, and
R.
Shepard
,
Chem. Rev.
112
,
108
(
2012
).
3.
F. A.
Evangelista
,
J. Chem. Phys.
149
,
030901
(
2018
).
4.
D.
Mukherjee
,
R. K.
Moitra
, and
A.
Mukhopadhyay
,
Mol. Phys.
30
,
1861
(
1975
).
5.
D.
Mukherjee
,
R. K.
Moitra
, and
A.
Mukhopadhyay
,
Mol. Phys.
33
,
955
(
1977
).
6.
I.
Lindgren
,
Int. J. Quantum Chem.
14
,
33
(
1978
).
7.
A.
Haque
and
U.
Kaldor
,
Chem. Phys. Lett.
117
,
347
(
1985
).
8.
I.
Lindgren
and
D.
Mukherjee
,
Phys. Rep.
151
,
93
(
1987
).
9.
R. J.
Bartlett
,
Annu. Rev. Phys. Chem.
32
,
359
(
1981
).
10.
J. A.
Pople
,
R.
Krishnan
,
H. B.
Schlegel
, and
J. S.
Binkley
,
Int. J. Quantum Chem.
14
,
545
(
1978
).
11.
H. J.
Werner
and
P. J.
Knowles
,
J. Chem. Phys.
89
,
5803
(
1988
).
12.
B.
Jeziorski
and
H. J.
Monkhorst
,
Phys. Rev. A
24
,
1668
(
1981
).
13.
X.
Li
and
J.
Paldus
,
J. Chem. Phys.
102
,
8897
(
1995
).
14.
X.
Li
and
J.
Paldus
,
J. Chem. Phys.
107
,
6257
(
1997
).
15.
U. S.
Mahapatra
,
B.
Datta
, and
D.
Mukherjee
,
Mol. Phys.
94
,
157
(
1998
).
16.
J.
Pittner
,
P.
Nachtigall
,
P.
Čársky
,
J.
Mášik
, and
I.
Hubač
,
J. Chem. Phys.
110
,
10275
(
1999
).
17.
M.
Hanrath
,
J. Chem. Phys.
123
,
084102
(
2005
).
18.
L.
Kong
,
K. R.
Shamasundar
,
O.
Demel
, and
M.
Nooijen
,
J. Chem. Phys.
130
,
114101
(
2009
).
19.
N.
Herrmann
and
M.
Hanrath
,
J. Chem. Phys.
153
,
164114
(
2020
).
20.
M.
Mörchen
,
L.
Freitag
, and
M.
Reiher
,
J. Chem. Phys.
153
,
244113
(
2020
).
21.
T.
Yanai
and
G. K.-L.
Chan
,
J. Chem. Phys.
124
,
194106
(
2006
).
22.
Z.
Chen
and
M. R.
Hoffmann
,
J. Chem. Phys.
137
,
014108
(
2012
).
23.
K.
Andersson
,
P.-Å.
Malmqvist
, and
B. O.
Roos
,
J. Chem. Phys.
96
,
1218
(
1992
).
24.
25.
P. M.
Kozlowski
and
E. R.
Davidson
,
J. Chem. Phys.
100
,
3672
(
1994
).
26.
M. R.
Hoffmann
,
J. Phys. Chem.
100
,
6125
(
1996
).
27.
C.
Angeli
,
R.
Cimiraglia
,
S.
Evangelisti
,
T.
Leininger
, and
J.-P.
Malrieu
,
J. Chem. Phys.
114
,
10252
(
2001
).
28.
R. K.
Chaudhuri
,
K. F.
Freed
,
G.
Hose
,
P.
Piecuch
,
K.
Kowalski
,
M.
Włoch
,
S.
Chattopadhyay
,
D.
Mukherjee
,
Z.
Rolik
,
Á.
Szabados
,
G.
Tóth
, and
P. R.
Surján
,
J. Chem. Phys.
122
,
134105
(
2005
).
30.
S.
Mao
,
L.
Cheng
,
W.
Liu
, and
D.
Mukherjee
,
J. Chem. Phys.
136
,
024105
(
2012
).
31.
W.
Liu
and
M. R.
Hoffmann
,
Theor. Chem. Acc.
133
,
1481
(
2014
).
32.
S.
Sharma
and
G. K.-L.
Chan
,
J. Chem. Phys.
141
,
111101
(
2014
).
33.
A.
Sen
,
S.
Sen
,
P. K.
Samanta
, and
D.
Mukherjee
,
J. Comput. Chem.
36
,
670
(
2015
).
34.
C.
Li
and
F. A.
Evangelista
,
J. Chem. Theory Comput.
11
,
2097
(
2015
).
35.
N.
Zhang
,
W.
Liu
, and
M. R.
Hoffmann
,
J. Chem. Theory Comput.
16
,
2296
(
2020
).
36.
G. H.
Booth
,
A. J. W.
Thom
, and
A.
Alavi
,
J. Chem. Phys.
131
,
054106
(
2009
).
37.
A. J. W.
Thom
,
Phys. Rev. Lett.
105
,
263004
(
2010
).
38.
39.
G. K.-L.
Chan
and
S.
Sharma
,
Annu. Rev. Phys. Chem.
62
,
465
(
2011
).
40.
S.
Knecht
,
E. D.
Hedegård
,
S.
Keller
,
A.
Kovyrshin
,
Y.
Ma
,
A.
Muolo
,
C. J.
Stein
, and
M.
Reiher
,
Chimia Int. J. Chem.
70
,
244
(
2016
).
41.
A. A.
Holmes
,
N. M.
Tubman
, and
C. J.
Umrigar
,
J. Chem. Theory Comput.
12
,
3674
(
2016
).
42.
J. E.
Deustua
,
J.
Shen
, and
P.
Piecuch
,
Phys. Rev. Lett.
119
,
223003
(
2017
).
43.
C. J. C.
Scott
,
R.
Di Remigio
,
T. D.
Crawford
, and
A. J. W.
Thom
,
J. Phys. Chem. Lett.
10
,
925
(
2019
).
44.
M.-A.
Filip
,
C. J. C.
Scott
, and
A. J. W.
Thom
,
J. Chem. Theory Comput.
15
,
6625
(
2019
).
45.
A.
Baiardi
and
M.
Reiher
,
J. Chem. Phys.
152
,
040903
(
2020
).
46.
P. G.
Szalay
and
R. J.
Bartlett
,
J. Chem. Phys.
103
,
3600
(
1995
).
47.
T. H.
Schucan
and
H. A.
Weidenmüller
,
Ann. Phys.
76
,
483
(
1973
).
48.
D.
Mukherjee
,
Chem. Phys. Lett.
125
,
207
(
1986
).
49.
D.
Mukherjee
,
Int. J. Quantum Chem.
30
,
409
(
1986
).
50.
D.
Mukhopadhyay
and
D.
Mukherjee
,
Chem. Phys. Lett.
163
,
171
(
1989
).
51.
J. P.
Malrieu
,
P.
Durand
, and
J. P.
Daudey
,
J. Phys. A: Math. Gen.
18
,
809
(
1985
).
52.
D.
Mukhopadhyay
,
B.
Datta (nee Kundu)
, and
D.
Mukherjee
,
Chem. Phys. Lett.
197
,
236
(
1992
).
53.
54.
R.
Maitra
,
D.
Sinha
, and
D.
Mukherjee
,
J. Chem. Phys.
137
,
024105
(
2012
).
55.
A.
Banerjee
and
J.
Simons
,
Int. J. Quantum Chem.
19
,
207
(
1981
).
56.
D.
Mukherjee
, in
Recent Progress in Many-Body Theories
, edited by
E.
Schachinger
,
H.
Mitter
, and
H.
Sormann
(
Springer US
,
Boston, MA
,
1995
), Vol. 4, pp.
127
133
.
57.
M.
Hanauer
and
A.
Köhn
,
J. Chem. Phys.
134
,
204111
(
2011
).
58.
J.-P.
Malrieu
,
J.-L.
Heully
, and
A.
Zaitsevskii
,
Theor. Chim. Acta
90
,
167
(
1995
).
59.
B. O.
Roos
and
K.
Andersson
,
Chem. Phys. Lett.
245
,
215
(
1995
).
60.
N.
Forsberg
and
P.-Å.
Malmqvist
,
Chem. Phys. Lett.
274
,
196
(
1997
).
61.
H. J. J.
van Dam
,
J. H.
van Lenthe
, and
P. J. A.
Ruttink
,
Int. J. Quantum Chem.
72
,
549
(
1999
).
62.
M. R.
Hoffmann
and
J.
Simons
,
J. Chem. Phys.
88
,
993
(
1988
).
63.
U.
Sinha Mahapatra
,
B.
Datta
, and
D.
Mukherjee
,
J. Phys. Chem. A
103
,
1822
(
1999
).
64.
R.
Pauncz
,
Spin Eigenfunctions: Construction and Use
(
Plenum Press
,
New York, London
,
1979
).
65.
E.
Giner
,
C.
Angeli
,
Y.
Garniron
,
A.
Scemama
, and
J.-P.
Malrieu
,
J. Chem. Phys.
146
,
224108
(
2017
).
66.
A.
Sen
,
S.
Sen
, and
D.
Mukherjee
,
J. Chem. Theory Comput.
11
,
4129
(
2015
).
67.
A.
Zaitsevskii
and
J.-P.
Malrieu
,
Chem. Phys. Lett.
233
,
597
(
1995
).
68.
A.
Zaitsevskii
and
J.-P.
Malrieu
,
Chem. Phys. Lett.
250
,
366
(
1996
).
69.
A.
Zaitsevskii
and
J.-P.
Malrieu
,
Theor. Chem. Acc.
96
,
269
(
1997
).
70.
S.
Sen
,
A.
Shee
, and
D.
Mukherjee
,
J. Chem. Phys.
137
,
074104
(
2012
).
71.
S.
Sen
,
A.
Shee
, and
D.
Mukherjee
,
J. Chem. Phys.
148
,
054107
(
2018
).
72.
D.
Chakravarti
,
S.
Sen
, and
D.
Mukherjee
, “
Two systematically improvable spin-adapted state-specific coupled cluster theories (UGA-SSMRCC): applications to potential energy surfaces
” (to be published).
73.
74.
G. M. J.
Barca
,
C.
Bertoni
,
L.
Carrington
,
D.
Datta
,
N.
De Silva
,
J. E.
Deustua
,
D. G.
Fedorov
,
J. R.
Gour
,
A. O.
Gunina
,
E.
Guidez
,
T.
Harville
,
S.
Irle
,
J.
Ivanic
,
K.
Kowalski
,
S. S.
Leang
,
H.
Li
,
W.
Li
,
J. J.
Lutz
,
I.
Magoulas
,
J.
Mato
,
V.
Mironov
,
H.
Nakata
,
B. Q.
Pham
,
P.
Piecuch
,
D.
Poole
,
S. R.
Pruitt
,
A. P.
Rendell
,
L. B.
Roskop
,
K.
Ruedenberg
,
T.
Sattasathuchana
,
M. W.
Schmidt
,
J.
Shen
,
L.
Slipchenko
,
M.
Sosonkina
,
V.
Sundriyal
,
A.
Tiwari
,
J. L.
Galvez Vallejo
,
B.
Westheimer
,
M.
Włoch
,
P.
Xu
,
F.
Zahariev
, and
M. S.
Gordon
,
J. Chem. Phys.
152
,
154102
(
2020
).
75.
H.-J.
Werner
,
P. J.
Knowles
,
G.
Knizia
,
F. R.
Manby
, and
M.
Schütz
,
Wiley Interdiscip. Rev.: Comput. Mol. Sci.
2
,
242
(
2012
).
76.
D.
Tzeli
and
A.
Mavridis
,
J. Phys. Chem. A
105
,
1175
(
2001
).
77.
D.
Tzeli
and
A.
Mavridis
,
J. Phys. Chem. A
105
,
7672
(
2001
).
78.
H.
Partridge
and
S. R.
Langhoff
,
J. Chem. Phys.
74
,
2361
(
1981
).
79.
M. W.
Schmidt
,
J.
Ivanic
, and
K.
Ruedenberg
,
J. Phys. Chem. A
114
,
8687
(
2010
).
80.
M.
Kolbuszewski
and
J. S.
Wright
,
Can. J. Chem.
71
,
1562
(
1993
).
81.
D.
Theis
,
Y. G.
Khait
,
S.
Pal
, and
M. R.
Hoffmann
,
Chem. Phys. Lett.
487
,
116
(
2010
).
82.
M. B.
Lepetit
and
J. P.
Malrieu
,
Chem. Phys. Lett.
169
,
285
(
1990
).
83.
A.
Kalemos
,
J. Chem. Phys.
145
,
214302
(
2016
).
84.
W.-Z.
Li
and
M.-B.
Huang
,
Chem. Phys.
315
,
133
(
2005
).
85.
D.
Datta
and
D.
Mukherjee
,
J. Chem. Phys.
134
,
054122
(
2011
).
86.
M.
Farjallah
,
C.
Ghanmi
, and
H.
Berriche
,
Russ. J. Phys. Chem. A
86
,
1226
(
2012
).
87.
S.
Pathak
,
L.
Lang
, and
F.
Neese
,
J. Chem. Phys.
147
,
234109
(
2017
).
88.
S.
Mahmoud
,
M.
Bechelany
,
P.
Miele
, and
M.
Korek
,
J. Quant. Spectrosc. Radiat. Transfer
151
,
58
(
2015
).
89.
C. W.
Bauschlicher
and
H.
Partridge
,
Chem. Phys. Lett.
257
,
601
(
1996
).
90.
S. P.
Karna
and
F.
Grein
,
Chem. Phys.
98
,
207
(
1985
).
91.
F.
Spiegelmann
and
J. P.
Malrieu
,
J. Phys. B: At. Mol. Phys.
17
,
1235
(
1984
).
92.
H.
Nakano
,
J. Chem. Phys.
99
,
7983
(
1993
).
93.
J.
Finley
,
P.-Å.
Malmqvist
,
B. O.
Roos
, and
L.
Serrano-Andrés
,
Chem. Phys. Lett.
288
,
299
(
1998
).
94.
A. A.
Granovsky
,
J. Chem. Phys.
134
,
214113
(
2011
).
95.
S.
Sharma
,
G.
Jeanmairet
, and
A.
Alavi
,
J. Chem. Phys.
144
,
034103
(
2016
).
96.
C.
Angeli
,
J. Comput. Chem.
30
,
1319
(
2009
).

Supplementary Material

You do not currently have access to this content.