Stability and bonding in the ground and excited
states of lithium fluoride Lin F clusters
Somnath Bhowmick, Denis Hagebaum-Reignier, Gwang-Hi Jeung
Chimie ThéOrique et Modèles (CTOM),
Institut des Sciences Moléculaires de Marseille, France
GdR Correl meeting, Marseilles
8 july 2015
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
1 / 14
Outline
Hyperlithiated clusters
Insertion mechanism and bonding in Li2 F/F−
Low-lying states of Lin F clusters
Concluding remarks
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
2 / 14
Hyperlithiated clusters
Hyperlithiated clusters Li3 O, Li4 O, Li5 O first observed in the gas
phase (1980’s)
"Are CLi6 , NLi5 , OLi4 ...hypervalent ?"
(Schleyer, 1983)
⇒ Hyperlithiated ALin molecules : A− in a metallic Li+
n cage
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
3 / 14
Hyperlithiated clusters
Hyperlithiated clusters Li3 O, Li4 O, Li5 O first observed in the gas
phase (1980’s)
"Are CLi6 , NLi5 , OLi4 ...hypervalent ?"
(Schleyer, 1983)
⇒ Hyperlithiated ALin molecules : A− in a metallic Li+
n cage
Hyperlithiated clusters are "superalkalis"
(Boldyrev et al., 1982)
⇒ very low I.Ps (' 4.0 eV) << I.P of Li atom (5.4 eV)
Building blocks for novel materials with unique properties
(magnetism, non-linear optics . . . )
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
3 / 14
Lithium fluoride clusters
Motivations
Experimental evidence of Lin F clusters with n = 2 − 6
(2000’s)
Model for the study of adsorption on a metallic surface : role of
excited states ?
→
Covalent and ionic interactions are expected along the reaction
path ⇒ multireference methods (CASSCF, MRCI-F12)
Li2 + F → Li2 F : possible candidate for ultracold temperature
reactions (Lane et al., 2010). Insertion mechanism ?
Li2 + F− → Li2 F− ? no study so far
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
4 / 14
Li2 +F potential energy curves
4.0
Energy (eV)
2.0
r=2.67Å
Li2(3Πu) + F
F/F-
Li2( Σu ) + F
3
0.0
+
Li2(X Σg ) + F
1
+
−2.0
Z
R
Qeff on F
−4.0
3 2A1
2 2A1
1 2A1
−6.0
0.5
Li
Li
r
X
0.0
−0.5
−1.0
Qeff =
1
2
3
4
5
6
R (Å)
7
8
9
10
µz
R
CAS(7,8)/MRCI-F12, AVTZ
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
5 / 14
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Li2 +F potential energy curves
4.0
Energy (eV)
2.0
r=2.67Å
Li2(3Πu) + F
F/F-
Li2( Σu ) + F
3
0.0
+
Li2(X Σg ) + F
1
+
−2.0
Z
R
Qeff on F
−4.0
3 2A1
2 2A1
1 2A1
−6.0
0.5
Li
Li
r
X
0.0
−0.5
−1.0
Qeff =
1
2
3
4
5
6
R (Å)
7
8
9
10
µz
R
CAS(7,8)/MRCI-F12, AVTZ
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
5 / 14
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Li2 +F potential energy curves
4.0
Li2 ( Σg ) + F
Li2(3Πu) + F
+ 2
Energy (eV)
2.0
+
−
r=2.67Å
IP−EA
Li2( Σu ) + F
3
0.0
+
F/F-
Li2(X Σg ) + F
1
+
−2.0
Z
R
Qeff on F
−4.0
3 2A1
2 2A1
1 2A1
−6.0
0.5
Li
Li
r
X
0.0
−0.5
−1.0
Qeff =
1
2
3
4
5
6
R (Å)
7
8
9
10
µz
R
CAS(7,8)/MRCI-F12, AVTZ
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
5 / 14
Y
Li2 +F potential energy curves
4.0
Li2 ( Σg ) + F
+ 2
Energy (eV)
2.0
+
−
r=2.67Å
F/F-
0.0
−2.0
Z
R
Qeff on F
−4.0
3 2A1
2 2A1
1 2A1
−6.0
0.5
Li
Li
r
X
0.0
−0.5
−1.0
Qeff =
1
2
3
4
5
6
R (Å)
7
8
9
10
µz
R
CAS(7,8)/MRCI-F12, AVTZ
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
5 / 14
Y
Li2 +F potential energy curves
4.0
Li2 ( Σg ) + F
Li2+(2Σu+) + F−
+ 2
Energy (eV)
2.0
+
r=2.67Å
F/F-
0.0
−2.0
Z
R
2
1
3
2
1
−4.0
Qeff on F
−
−6.0
0.5
2
B2
B2
A1
2
A1
2
A1
2
2
Li
Li
r
X
0.0
−0.5
−1.0
Qeff =
1
2
3
4
5
6
R (Å)
7
8
9
10
µz
R
CAS(7,8)/MRCI-F12, AVTZ
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
5 / 14
Y
Li2 +F potential energy curves
4.0
Li2+(2Πu) + F−
Li2 ( Σg ) + F
Li2+(2Σu+) + F−
+ 2
Energy (eV)
2.0
+
r=2.67Å
F/F-
0.0
−2.0
2
1
2
1
3
2
1
−4.0
Qeff on F
−
−6.0
0.5
Z
R
2
B1
B1
2
B2
2
B2
2
A1
2
A1
2
A1
2
Li
Li
r
X
0.0
−0.5
−1.0
Qeff =
1
2
3
4
5
6
R (Å)
7
8
9
10
µz
R
CAS(7,8)/MRCI-F12, AVTZ
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
5 / 14
Y
Li2 +F− potential energy curves
2.0
Energy (eV)
1.0
Li2( Σu ) + F
3
+
−
r=2.67Å
F/F-
0.0
Li2(X1Σg+) + F−
−1.0
Z
R
−2.0
Qeff on F
−3.0
Li
Li
1 3A1
1 1A1
−4.0
0.5
r
X
0.0
−0.5
−1.0
Qeff =
0
1
2
3
4
5
R (Å)
6
7
8
9
10
µz
R
CAS(8,9)/MRCI-F12, AVTZ
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
6 / 14
Y
Li2 +F− potential energy curves
2.0
Energy (eV)
1.0
Li2( Σu ) + F
3
−
r=2.67Å
F/F-
0.0
Li2(X1Σg+) + F−
−1.0
Z
R
−2.0
1
1
1
1
−3.0
Qeff on F
+
−4.0
0.5
3
B2
B2
A1
1
A1
1
Li
Li
3
r
X
0.0
−0.5
−1.0
Qeff =
0
1
2
3
4
5
R (Å)
6
7
8
9
10
µz
R
CAS(8,9)/MRCI-F12, AVTZ
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
6 / 14
Y
Li2 +F− potential energy curves
2.0
Energy (eV)
1.0
Li2( Σu ) + F
3
−
r=2.67Å
F/F-
0.0
Li2(X1Σg+) + F−
−1.0
Z
R
−2.0
1
1
1
1
1
−3.0
Qeff on F
+
−4.0
0.5
3
B1
B2
B2
3
A1
1
A1
3
1
Li
Li
r
X
0.0
−0.5
−1.0
Qeff =
0
1
2
3
4
5
R (Å)
6
7
8
9
10
µz
R
CAS(8,9)/MRCI-F12, AVTZ
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
6 / 14
Y
Bond analysis of the low-lying states of Li2 F−
4 The ground state is linear, the excited states are bent
4 The triplet states are mono-configurational, the singlets are
multi-configurational
Li2 F−
C2v
1
1
3 +
Σ+
g ≈ Σu
A1
↑↓
13 A1
B2
↑
or
↑↓
3
11 B2
↑
↑
and
and
↑
↑
and
↓
⇒ 3c/4e− σ̂ type "long bonding" a as in Li−Be−Li :
a.
C. Landis & F. Weinhold, Inorg. Chem. 52, 2013, 5154
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
7 / 14
Low-lying states of Lin F
Choice of clusters and method
clusters
The Lin clusters correspond to a (100) plane of the bcc crystal
(r=3.51Å )
The Lin F/F− clusters have a C2v symmetry
Method : CAS(n+5,11)/MRCI, AVTZ − ECP for n = 8
Bridge and on-top adsorption sites
n=
4
5
6t
6b
8
bcc
bcc
on-top
bridge
bridge
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
8 / 14
Low-lying states of Lin F
Lin F− potential energy curves
clusters
Li4 F−
Li8 F−
1.5
Energy (eV)
Energy (eV)
1.5
1.0
0.5
1.0
0.5
A2
B1
B2
A1
0.0
0.0
0.5
1.0
A2
B1
B2
A1
0.0
1.5
z (Å)
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
−2.0
−1.5
−1.0
−0.5
0.0
z (Å)
0.5
GdR Correl, Marseilles − 8 july 2015
1.0
1.5
9 / 14
Low-lying states of Lin F clusters
Vertical excitation energies
Lin F−
Vertical excitation energy (eV)
Lin F
1
A2
B2
B1
A1
1
0.5
A2
B2
B1
A1
0.5
0
0
0
2
4
5
6t 6b
8
0
2
Cluster size n
n=
2
4
5
6t 6b
8
Cluster size n
4
5
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
6t
6b
8
GdR Correl, Marseilles − 8 july 2015
10 / 14
Low-lying states of Lin F clusters
Stabilization energies
Lin F clusters are more stabilized than Lin F− clusters
Bridge positions are favoured
The second layer is stabilizing
LinF- clusters
LinF clusters
-2
Stabilization energy (eV)
Stabilization energy (eV)
-2
-3
A2
B2
B1
A1
-4
-5
-6
-7
-3
A2
B2
B1
A1
-4
-5
-6
-7
0
2
4
5
6t 6b
8
Cluster size n
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
0
2
4
5
6t 6b
8
Cluster size n
GdR Correl, Marseilles − 8 july 2015
11 / 14
Concluding remarks
4 Lithium fluoride clusters display charge-transfer properties,
covalent/ionic interactions
4 Correlated ab initio methods are needed to properly describe
their dissociation
4 Ground and excited states of Li2 F and Li2 F− display unusual
electronic structures
4 Existence of low-lying states (< 0.5 eV above the GS) in Lin F
clusters
4 Strong stabilization of the Lin F clusters
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
12 / 14
Future work
Bonding and dipole moment analysis of Lin F clusters
The computation of the excited states on bigger Lin F (n > 10)
clusters is ongoing
Computation of first ionization (neutral) and detachment
(anionic) energies → superalkalis
Valence-Bond description of the excited states of the small
complexes → projection method developped in our group
(J. Racine & S. Humbel)
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
13 / 14
Aknowledgments
Somnath Bhowmick (PhD)
Julien Racine (PhD)
Paola Nava
Yannick Carissan
Jean-Marc Mattalia
Gwang-Hi Jeung
Stéphane Humbel
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
14 / 14
Optimized states of Li2 F and Li2 F−
Li2 F−
Li2 F
r1 = 2.67 Å (free Li2 )
r2 = 3.51 Å (crystal)
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
15 / 14
Bond analysis of the low-lying states of Li2 F
4 The low-lying states are mono-configurational
4 The ground state is bent, the excited states are linear
X̃ 2 A1
12 A1
Li2 F
C2v
↑
2 +
Σu
12 B2
↑
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
2
Πu
12 B1
↑
22 A1
↑
GdR Correl, Marseilles − 8 july 2015
16 / 14
Li2 F potential energy surfaces
12A1 state (Ground state)
22A1 state
10
10
1
1
0.5
0
8
8
0
6
−2
0.4
−3
0
4
−0.8
−1.6
−0.5
R (Å)
R (Å)
−1
6
−1
−1.5
4
−2
0.4
−2.5
−4
−2.4
2
−4
−4.8
0.8
2
−3.2
−5
−6.0
−3.2
−1.6
−2.4
−3
0
−3.5
−4.0
0
0
−6
2
2.5
3
3.5
4
4.5
5
−4
2
2.5
F/F-
r (Å)
3
3.5
4
4.5
5
r (Å)
Z
R
Li
Li
Y
r
X
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
17 / 14
Li2 F potential energy surfaces
12B1 state
12B2 state
10
10
1
1
0.5
0
8
8
0
0
−1
−1
0.4
−1.5
4
−2
R (Å)
R (Å)
−0.5
6
6
0
0.8
−2
−3
4
0.4
−2.5
0
2
0
−2.8
−2.4
−0.4
0.8
−4.0
−4
−0.8
2
−3
−2
−5
−3.2
−4
−4.8
−3.5
−5.2
0
0
−4
2
2.5
3
3.5
4
4.5
5
−6
2
2.5
F/F-
r (Å)
3
3.5
4
4.5
5
r (Å)
Z
R
Li
Li
Y
r
X
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
17 / 14
Li2 F− potential energy surfaces
11A1 state (Ground state)
13B2 state
10
1
10
0
8
1
0.5
8
0.6
0
6
−1
0.4
0.2
4
−2
0
R (Å)
R (Å)
−0.5
6
−1
1
−1.5
0.6
4
−2
0.2
−0.2
−0.4
2
−3.2
−2.5
−1.4
2
−3
−2.8
−2.4
−3.4
−3
−3.8
0
−4
2
2.5
3
3.5
−2.2
−3.5
−4.0
0
−3
−2.6
4
4.5
5
−4
2
2.5
F/F-
r (Å)
3
3.5
4
4.5
5
r (Å)
Z
R
Li
Li
Y
r
X
S. Bhowmick, D. Hagebaum-Reignier, G.-H. Jeung
GdR Correl, Marseilles − 8 july 2015
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