1. No category

RMN premiers principes appliquée à l’étude
des verres de phosphates
Filipe Vasconcelos
Radboud University Nijmegen,
Electronic Structure of Materials
École thématique GDR-Verres
Marcoule - Mai 2011
Filipe Vasconcelos
RMN premiers principes
1
Outline
Introduction
General context
Some elements of the methodology
NMR First Principles applied to Glass
8 Motivations
8 How to generate glass configurations ?
8 Case study : Sodium metaphosphate glass (NaPO3 )
{ NMR results (spectra, correlations, . . . )
{ EFG distributions
{ Extended Czjzek Model
NMR parameters and structure
8 Potential energy landscape (PEL) in glass science.
8 NMR parameters revealing the PEL
General Conclusions
Filipe Vasconcelos
RMN premiers principes
2
Outline
Introduction
General context
Some elements of the methodology
NMR First Principles applied to Glass
8 Motivations
8 How to generate glass configurations ?
8 Case study : Sodium metaphosphate glass (NaPO3 )
{ NMR results (spectra, correlations, . . . )
{ EFG distributions
{ Extended Czjzek Model
NMR parameters and structure
8 Potential energy landscape (PEL) in glass science.
8 NMR parameters revealing the PEL
General Conclusions
Filipe Vasconcelos
RMN premiers principes
2
Introduction
General context
NMR
CRYSTAL
STRUCTURE
XRD
MD
Filipe Vasconcelos
GLASS
AMORPHOUS
DISORDER
DFT
RMN premiers principes
3
Introduction
General context
NMR
CRYSTAL
STRUCTURE
XRD
MD
GLASS
AMORPHOUS
DISORDER
DFT
NMR :
8 Better resolution → more information
Filipe Vasconcelos
RMN premiers principes
3
Introduction
Solid-State Nuclear Magnetic Resonance (SSNMR)
Dynamic
Structure
Interaction
CS
Q
D
J
Filipe Vasconcelos
Name
Chemical Shift
Quadrupolar
Dipolar coupling
Indirect spin-spin coupling
RMN premiers principes
Tensor
CSA
EFG
D
J
Parameters
δiso , ∆CS , ηCS
CQ ,ηQ
r
Jiso
4
Introduction
Solid-State Nuclear Magnetic Resonance (SSNMR)
Dynamic
Structure
Interaction
CS
Q
D
J
Filipe Vasconcelos
Name
Chemical Shift
Quadrupolar
Dipolar coupling
Indirect spin-spin coupling
RMN premiers principes
Tensor
CSA
EFG
D
J
Parameters
δiso , ∆CS , ηCS
CQ ,ηQ
r
Jiso
4
Introduction
Solid-State Nuclear Magnetic Resonance (SSNMR)
Dynamic
Structure
Interaction
CS
Q
D
J
Filipe Vasconcelos
Name
Chemical Shift
Quadrupolar
Dipolar coupling
Indirect spin-spin coupling
RMN premiers principes
Tensor
CSA
EFG
D
J
Parameters
δiso , ∆CS , ηCS
CQ ,ηQ
r
Jiso
4
Introduction
Overview of 17 O
Properties
8 Predominant nucleus in oxides based glasses
8 Two different role in the structure ( BO , NBO )
8 Wide chemical shift range
8 Low natural abundance (0.037%)
8 Quadrupolar interaction with the surrounding EFG
Quadrupolar Interaction
8 I=5/2
8 Q=25.58 mb
 ηQ −1
2
EFG : V = Vzz  0
0
Filipe Vasconcelos
RMN premiers principes
0
−ηQ −1
2
0

0
0
1
5
Introduction
Elements of methodology
Experimental (NMR)
8 Isotopic enrichment (17 O)
8 High-Field (18.8 T)
8 Multi-nuclei (23 Na, 31 P, 17 O)
8 High-resolution experiments (MAS, MQMAS)
Theoretical (Modelisation)
8 Electronic Struct. : DFT
8 NMR parameters : DFT-PAW/GIPAW
8 MD : classical, ab-initio
8 Spectra simulation
8 Used codes :
{ VASP, Quantum-ESPRESSO, PARATEC
{ DL_POLY
{ DMFIT, simpson, gen_mas, gen_MQMAS
Filipe Vasconcelos
RMN premiers principes
6
Outline
Introduction
General context
Some elements of the methodology
NMR First Principles applied to Glass
8 Motivations
8 How to generate glass configurations ?
8 Case study : Sodium metaphosphate glass (NaPO3 )
{ NMR results (spectra, correlations, . . . )
{ EFG distributions
{ Extended Czjzek Model
NMR parameters and structure
8 Potential energy landscape (PEL) in glass science.
8 NMR parameters revealing the PEL
General Conclusions
Filipe Vasconcelos
RMN premiers principes
7
Sodium metaphosphate glass
3QMAS at 18.8T of NaPO3
Non-bridging oxygens
8 small distribution (CQ , ηQ ) → local order
8 large distribution δiso → long distance disorder
F. Vasconcelos et al., Inorg. Chem., 47 7327 (2008)
Filipe Vasconcelos
RMN premiers principes
8
How to generate glass configurations ?
For NMR First-Principles
High−T
(3500 K)
What do we need ?
classical−MD
8 Accurate structures ,
8 Good statistics (∼ 1000 sites)
8 Small boxes (∼ 100 atoms)
Low−T
DFT
(300 K)
0
TIME
Which methods ?
Molecular Dynamics (MD) :
8 "Ab-initio" MD : accurate, time consuming, few configurations
8 Classical MD : fast, many configurations, empirical Force-Fields
8 Combined approach : classical and first-principles
8 DL_POLY+ VASP (PARATEC : DFT-PAW/GIPAW)
Filipe Vasconcelos
RMN premiers principes
9
Q1
NaPO3 (metaphosphate)
Structural constraints
31 P
Q3
(Na2 O)x −(P2 O5 ) 1-x
Na−Na
Na−O
O−O
P−P
P−NBO
P−BO
MD ref [1]
d (Å)
3.1
2.31
2.51
3.18
1.50
1.59
Neutron ref [2]
d (Å)
3.07
2.33
2.52
2.93
1.48
1.61
our model
d (Å)
3.35
2.35
2.55
2.95
1.45
1.65
Q1
Q2
Q3
25%
50%
25%
0%
∼100%
0%
3.5%
93%
3.5%
atomic pair
Q2
[1] Speghini et al. PCCP 1 p173 (1999)
[2] Pickup et al. J. Phys. Condens. Matter 19 p415116 (2007)
Filipe Vasconcelos
RMN premiers principes
10
NMR/DFT-GIPAW results on MD configurations
NMR 17 O
dimension isotrope (ppm)
200
-60
80
40
0
O déplacement chimique (ppm)
NBO
BO
-90
150
Filipe Vasconcelos
120
160
17
RMN premiers principes
125
100
75
dimension MAS (ppm)
50
11
DFT-GIPAW results on MD configurations
Clark-Grandinetti correlation 17 O
CQ (Ω) = a
1
cos Ω
+
2
cos Ω − 1
ηQ (Ω) = b
cos Ω
1
−
2
cos Ω − 1
Ω
!β
1
0,8
10
ηQ
CQ (MHz)
11
!α
9
0,6
0,4
8
7
100
Filipe Vasconcelos
0,2
120
140
160
angle Ω (deg)
180
0
100
RMN premiers principes
120
140
160
angle Ω(deg)
180
12
Quadrupolar parameter distributions
How can we use this new information ?
6
12
4
8
2
4
0
0
0.2
ηQ
0.4
0.7
0.8
0.9
1
Vzz
4
0
5
4
3
3
2
8 extract experimental
quadrupolar parameters
see Charpentier et al.
(SiO2 )
8 better understand the
distribution of EFG tensor
2
1
0
1
0
0.2
0.4
0.6
ηQ
Filipe Vasconcelos
0.8
11
1.2
1.4
1.6
0
1.8
Vzz
RMN premiers principes
13
Czjzek Model
Gaussian isotropic Model for EFG distribution
Analytical formulation
P(Vzz , ηQ ) =
√ 1
V4 η
2πσ 5 zz Q
1−
2
ηQ
9
"
exp −
2
2
Vzz
(1+ηQ
/3)
2σ 5
#
[1]
[1] Czjzek et al. Phys. Rev. B 23 p2513 (1981)
[2] G. Le Caër et R. A. Brand J. Phys. Condens. Matter 10 p 10715 (1998)
Filipe Vasconcelos
RMN premiers principes
14
Czjzek Model
Example : Application to 27 Al in potassium aluminophosphate glass
(50(K2 O)x(Al2 O3 )(50-x)(P2 O5 ) )
Gaussian
Czjzek
AlO4
AlO6
AlO4
AlO5
exp
sim
5%
déplacement chimique (ppm) concentration (%)
80
AlO5
40
AlO6
70
60
70
35
60
30
50
25
40
20
30
15
10
20
10
0
-8
25
-10
50
40
30
20
52
50
-12
20
-14
48
-16
15
-18
46
0
5
10
15
% Al2O3
20
10
0
5
10
15
% Al2O3
-20
20 0
5
10
15
% Al2O3
20
DMFIT : Magn. Reson. Chem. 40 70-76 (2002)
Filipe Vasconcelos
RMN premiers principes
15
Discussion about the Czjzek model
an isotropic model
8 No structural information can be extracted from an isotropic
distribution [1]
8 In case of 17 O, some structural data can be deduced from
lineshape analysis. [2]
2
23
17
Na
4
O NBO
17
4
O BO
1
2
0
0
0,2 0,4 0,6 0,8
ηQ
0
1 0
2
0,2 0,4 0,6 0,8
ηQ
0
1 0
0,2 0,4 0,6 0,8
ηQ
1
[1] G. Caër et al., J. of Phys. : Condens. Matt. 22, 065402 (2010)
[2] F. Vasconcelos et al. ( coming soon ! ! ;)
Filipe Vasconcelos
RMN premiers principes
16
Extended Czjzek Model (Le Caër et al., 1998)
A perturbation of an anisotropic EFG tensor
V() = V0 + ρ VCzjzek
=
ρ||VCzjzek ||
||V0 ||
8 V0 : local EFG tensor local with Vzz (0) and η(0) fixed
8 VCzjzek : Czjzek tensor (isotropic noise)
6
P(Vzz>0)
(a)
5
ε
f(ηQ)
4
3
0.6
0.3
ρz
1
Filipe Vasconcelos
(b)
0.8
0.4
2
0
1
0.2
0.1
0
0.2
0.4
ηQ
0.6
0.8
1
RMN premiers principes
0
(c)
0
1
2
ε
3
4
17
Extended Czjzek Model
Quantification of the anisotropy part
6
5
ε = 0.093
ηQ(0) = 0.15
Vzz(0) = 0.853
4
3
2
1
0
0
0,2
0,4
0,6
ηQ
0,8
1 0,7
0,8
0,9
1
Vzz
4
8 ηQ and Vzz distributions
accurately reproduced
ε = 0.135
ηQ(0) = 0.43
Vzz(0) = 1.387
3
2
1
0
0
0,2
0,4
0,6
ηQ
Filipe Vasconcelos
0,8
11
1,2
1,4
1,6
1,8
Vzz
RMN premiers principes
18
Extended Czjzek Model
. . . looking for structural information
Reminder : Tensor distribution
8 tensor components are distributed not the eigenvalues
8 EFG tensor → 5 components (Ui , i = 1, 5)
8 Czjzek Model → all Ui components are normally distributed
15

P(Ui)
23
vxx
V = vxy
vxz
Na
10
5
0
-0,2
-0,1
0
0,1
0,2
Ui (u.a)
Filipe Vasconcelos
RMN premiers principes
vxy
vyy
vyz

vxz
vyz 
vzz
U1 = vzz /2
vxz
U2 = √
3
vyz
U3 = √
3
vxy
U4 = √
3
(vxx − vyy )
√
U5 =
2 3
19
Extended Czjzek Model
4
4
3
3
P(Uk)
P(U1)
. . . distributions of Ui components of 17 O in NaPO3 MD model
2
1
0
2
O NBO
17
O BO
1
-0.4
0
0
0.4
-0.4
0
U1
P(Uk)
2
1
0
-1
-0.5
0
U1
Filipe Vasconcelos
0.4
Uk
2
P(U1)
17
0.5
1
1
0
-1
-0.5
0
0.5
1
Uk
RMN premiers principes
20
Extended Czjzek Model
4
4
3
3
P(Uk)
P(U1)
. . . distributions of Ui components of 17 O in NaPO3 MD model
2
1
0
ONE CHARGE
2
O NBO
17
O BO
1
-0.4
0
0
0.4
-0.4
0
U1
P(Uk)
2
1
0
-1
-0.5
0
U1
Filipe Vasconcelos
0.4
Uk
2
P(U1)
17
0.5
1
1
0
-1
-0.5
0
0.5
1
Uk
RMN premiers principes
20
Extended Czjzek Model
4
4
3
3
P(Uk)
P(U1)
. . . distributions of Ui components of 17 O in NaPO3 MD model
2
1
0
17
2
1
-0.4
0
0
0.4
-0.4
0
U1
P(Uk)
2
1
0
-1
-0.5
0
U1
Filipe Vasconcelos
0.4
Uk
2
P(U1)
O NBO
0.5
1
TWO CHARGES
17
1
0
-1
-0.5
0
0.5
O BO
1
Uk
RMN premiers principes
20
Extended Czjzek Model
4
4
3
3
P(Uk)
P(U1)
. . . distributions of Ui components of 17 O in NaPO3 MD model
2
1
0
2
O NBO
17
O BO
1
-0.4
0
0
0.4
-0.4
0
U1
P(Uk)
2
1
0
-1
0.4
Uk
2
P(U1)
17
-0.5
0
U1
0.5
1
1
0
-1
-0.5
0
0.5
1
Uk
Distribution of EFG contains structural and geometric
information
Filipe Vasconcelos
RMN premiers principes
20
Perspective : CSA tensor
Distributions of CSA parameters (23 Na)
0.6
(a)
(b)
f(∆CS) × 10
f(ηCS)
1.5
1
0.5
0
I
I
0
0.2
0.4
0.6
ηCS
0.8
1
0.4
0.2
0
-40
-20
0
∆CS (ppm)
20
40
Czjzek distribution on the CSA parameters of 23 Na
asymetric and anistotropic CSA parameters plays the same role
as the EFG parameters
Filipe Vasconcelos
RMN premiers principes
21
Perspective : CSA
Distributions of tensor components BO and NBO (MD model)
5
5
A00 = −(1/ 3)[σxx + σyy + σzz ]
√
A10 = −(i/ 2)[σxy + σyx ]
A1±1 = −(1/2)[σzx − σxz ± i(σzy − σyz )]
√
A20 = (1/ 6)[3σzz − (σxx + σyy + σzz )]
P(Uk)
3
P(U1)
√
2
1
0
3
2
1
-100
0
0
-50
-40
0
U1
NBO
BO
"Czjzek"
P(ηCS)
A2±2 = (1/2)[σxx − σyy ± i(σxy − σyx )]
0
RMN premiers principes
40
Uk
A2±1 = ∓(1/2)[σxz + σzx ± i(σyz − σzy )]
Filipe Vasconcelos
NBO
BO
4
× 100
× 100
4
0,2
0,4
0,6
ηCS
0,8
1
22
Perspective : CSA
Distributions of tensor components BO and NBO (MD model)
5
5
A00 = −(1/ 3)[σxx + σyy + σzz ]
√
A10 = −(i/ 2)[σxy + σyx ]
A1±1 = −(1/2)[σzx − σxz ± i(σzy − σyz )]
√
A20 = (1/ 6)[3σzz − (σxx + σyy + σzz )]
P(Uk)
3
P(U1)
√
2
1
0
3
2
1
-100
0
0
-50
-40
0
U1
NBO
BO
"Czjzek"
P(ηCS)
A2±2 = (1/2)[σxx − σyy ± i(σxy − σyx )]
Experimentally difficult
to observe
RMN premiers principes
40
Uk
A2±1 = ∓(1/2)[σxz + σzx ± i(σyz − σzy )]
Filipe Vasconcelos
NBO
BO
4
× 100
× 100
4
0
0,2
0,4
0,6
ηCS
0,8
1
22
Conclusions
. . . from the study of this glass structure
Glass structure
8 MD + DFT/PAW-GIPAW are the principal tools to study glass
structure
8 Our structural model reproduces accurately NMR observations
8 NMR parameter domains are defined for a given compound
Extended Czjzek Model
8 Extended model can reproduce quadrupolar parameters
distribution observed on MD model
8 EFG tensor clearly presents local character
Filipe Vasconcelos
RMN premiers principes
23
Outline
Introduction
General context
Some elements of the methodology
NMR First Principles applied to Glass
8 Motivations
8 How to generate glass configurations ?
8 Case study : Sodium metaphosphate glass (NaPO3 )
{ NMR results (spectra, correlations, . . . )
{ EFG distributions
{ Extended Czjzek Model
NMR parameters and structure
8 Potential energy landscape (PEL) in glass science.
8 NMR parameters revealing the PEL
General Conclusions
Filipe Vasconcelos
RMN premiers principes
24
Potential Energy Landscape (PEL)
Concept
8 Function of N-body positions
Φ(R1 , ...RN ) [1]
8 Quatilative and quantitative
description of glass
transitions [2,3]
8 Relation between dynamics
and the sampling of PEL
thermodynamic and static
properties
[1] M. Goldstein , J. Chem. Phys., 51, 3728, (1969)
[3] S. Sastry, Nature, 409, 164 (2001)
[2] P. G. Debenedetti and F. H. Stillinger, Nature, 410, 259 (2001)
Filipe Vasconcelos
RMN premiers principes
25
Connection between NMR parameter and PEL
NMR
PEL
electronic structure
Ψ({ri }, {RI })
potential energy
Φ({RI })
Chemical selectivity
fixed for a given stoichiometry and density
Structural selectivity
Filipe Vasconcelos
RMN premiers principes
26
NMR parameters distribution/dispersion
Filipe Vasconcelos
RMN premiers principes
27
Vibrational "disorder" of EFG in NaCl-like structure
8 Binary-Mixture Lennard-Jones
potential
8 N = 1728 ; dt = 0.003 ; ρ = 1.58 ;
qA = +1 ; qB = -1
8 NVE ensemble (berendsen scaling)
4
4
2
2
0
0
-2
-4
0
1000
2000
30000
time step (dt=0.003)
Filipe Vasconcelos
0,2
1
1
0,8
0,8
0,6
0,6
0,4
0,4
-2
0,2
0,2
-4
0,4
0
ηQ
Vzz
8 (no electrostatic forces !)
0
P(Vzz)
RMN premiers principes
1000
2000
3000
time step (dt=0.003)
0,8 1,6
0
P(ηQ)
28
PEL/NMR representation framework
Transition Solid/Liquid
0,4
<Vzz>
0,2
<U²>-<U>²
atom A
atom B
both
0,3
0,1
0
-0,1
-0,2
0,4
0,8
1,2
0,611
2
0,4
6
0,609
5
0,608
0,607
0,606
1,2
1,6
2
T
T=2.0
T=1.0
T=0.4
4
3
2
0,605
1
0,604
0
0,5
1
1,5
2
0
T
Filipe Vasconcelos
0,8
7
0,61
<g(r)>
<ηQ>
1,6
T
RMN premiers principes
1
rAB
2
3
29
PEL/NMR representation framework
Conclusions
8 Simple connection between NMR/PEL
8 Structure selectivity of NMR
8 The acces to the NMR param. dynamics . . .
8 . . . a way to probe the dynamics of PEL
Challenging tasks
Experimental :
8 get access to the distribution of the anisotropic terms (separately)
8 get acces to the CSA tensors in solid state (in routine ,)
8 dynamics of NMR parameters in long-time scale ( ? ? ?)
Theoretical :
8 following the NMR parameters during the dynamics
Filipe Vasconcelos
RMN premiers principes
30
General Conclusions
NMR First-Principles is essential for glass structure
determination
8 Access to distribution (in particular η parameters)
8 Extended Czjzek approach is validated for 17 O
8 EFG tensor distribution contains structural information
8 CSA tensor can be characterized by Czjzek and extended Czjzek
models
NMR/PEL framework
8 . . . is elegant
8 . . . used in description of dynamics/structure properties of glass.
8 . . . brings challenging experimental and theoretical problems.
Filipe Vasconcelos
RMN premiers principes
31
Acknowledgement
Lille
Nijmegen
Sylvain Cristol
Laurent Delevoye
Jean-François Paul
Lionel Montagne
Chandrakala Gowda (NMR)
Ernst van Eck (NMR)
Arno Kentgens (NMR)
Rob de Groot (ESM)
Gilles de Wijs (ESM)
Collaborations
Georg Kresse (VASP)
Martijn Marsman (VASP)
Francesco Mauri (PARATEC)
Thibault Charpentier (Glass+NMR)
Gérard Le Caër (Extended Czjzek)
Filipe Vasconcelos
RMN premiers principes
32
Glass structure
Experimental approach
Experimental techniques
8 EXAFS → environment/short range
order
8 RAMAN → vibration mode (Boson’s
peak)
8 Neutron/XRay scattering → pair
distribution function T (r )
8 ...
8 Solid-State NMR → highly sensitive/
local : short, medium, (long ?) range
order
Filipe Vasconcelos
RMN premiers principes
33
Empirical Force Field
Charge of sodium
charge
qNa = +1
qNa = +0.2
no Na
Q0
1
3.1%
0
0%
0
0%
Q1
9
28.1%
5
15.6%
1
3.1%
Q2
11
34.4%
22
68.8%
30
93.8%
Q3
11
34.4%
5
15.6%
1
3.1%
Q4
0
0.000%
0
0%
0
0%
How can we avoid this « trick »
8 Test finite size effect
8 Test slower (or faster ?) quenching rate by 3 or 4 order magnitude
Filipe Vasconcelos
RMN premiers principes
34
NaPO3
Calculation details
8 160 atoms : 32Na-32P-96O, density ∼ 2.53 g/ml
8 quench 3500K -> 300K (rate 4 × 1012 K/s)
8 BKS empirical potential
8 NVE, equilibrated during 2 ps at each T
8 15 configurations.
-2855.5
’C_19/out_Etot_19’
-2856
-2856.5
-2857
-2857.5
-2858
-2858.5
-2859
0
Filipe Vasconcelos
2000
4000
6000
8000
10000
12000
RMN premiers principes
35
NaPO3 MD 17 O 3QMAS zoom
dimension isotrope (ppm)
-40
-50
-60
-70
100
125
75
50
dimension MAS (ppm)
Filipe Vasconcelos
RMN premiers principes
36
FIG
105
CQ (MHz)
100
δiso (ppm)
95
90
85
80
0,4
6
0,35
5,5
0
1
2
3
4
4
t (ps)
0,25
0
1
2
3
4
0,2
0
t (ps)
(a)
150
0,3
5
4,5
75
70
6,5
ηQ
Chapitre 3
1
2
3
4
t (ps)
(b)
100
50
150
100
50
déplacement chimique (ppm)
sites
O1
O2
O3
O4
O5
O6
Filipe Vasconcelos
δiso (ppm)
moyenne
écart-type
86.3
6.3
95.5
8.4
133.7
5.4
133.8
2.9
91.9
5.3
81.9
5.0
CQ (MHz)
moyenne
écart-type
5.20
0.37
5.30
0.52
7.82
0.28
7.74
0.20
5.13
0.28
5.27
0.28
RMN premiers principes
ηQ
moyenne
0.30
0.15
0.67
0.67
0.15
0.26
écart-type
0.04
0.03
0.08
0.06
0.03
0.04
37
FIG
Chapitre 3
sites
O1
O2
O3
O4
O5
O6
Filipe Vasconcelos
NVE à 400K
δiso (ppm) CQ (MHz)
86.3
5.20
95.5
5.30
133.7
7.82
133.9
7.74
91.9
5.13
81.9
5.27
ηQ
0.30
0.15
0.67
0.67
0.15
0.26
optimisé à 0K
δiso (ppm) CQ (MHz)
79.2
5.04
86.9
5.10
126.4
7.90
129.3
7.65
85.2
4.95
75.6
5.10
RMN premiers principes
ηQ
0.30
0.05
0.61
0.67
0.09
0.26
38
Anhydrous Sodium Phosphates
Na3 P3 O9
Na5 P3 O10
Na4 P2 O7
F. Vasconcelos et al., Inorg. Chem., 47 7327 (2008)
Filipe Vasconcelos
RMN premiers principes
39
Na3 P3 O9 : assisted assignment
DFT-GIPAW+MQMAS
MQMAS
Type
NBO
NBO
NBO
BO
CQ (MHz)
4.5
4.3
4.3
∼7.0
ηQ
0.3
0.4
0.1
∼0.6
δiso (ppm)
75.5
77.5
84.0
∼120
DFT-GIPAW
sites O
O1
O2
O3
O4
O5
O6
Type
NBO
NBO
BO
BO
NBO
NBO
CQ (MHz)
4.65
4.74
7.72
7.51
4.62
4.78
ηQ
0.31
0.07
0.61
0.66
0.09
0.26
δiso calc (ppm)
78.2
84.4
124.8
126.9
84.3
75.5
F. Vasconcelos et al., Inorg. Chem., 47 7327 (2008)
Filipe Vasconcelos
RMN premiers principes
40
Discussion
Correlation Structure/NMR
Observations
I
No correlation of NBO δiso with local
environment
I
CQ First coordination sphere
I
ηQ axial/equatorial positions,
covalent
Site O
O1
O2
O5
O6
Filipe Vasconcelos
Type
NBO
NBO
NBO
NBO
RMN premiers principes
CQ (MHz)
4.65
4.74
4.62
4.78
ηQ
0.31
0.07
0.09
0.26
δiso calc (ppm)
78.2
84.4
84.3
75.5
41