shape resonances localization and analysis by means of the single center expansion e-molecule...
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Shape resonances localization and Shape resonances localization and analysis by means of the Single Center analysis by means of the Single Center Expansion e-molecule scattering theoryExpansion e-molecule scattering theory
Andrea GrandiAndrea Grandiandand
N.Sanna and F.A.GianturcoN.Sanna and F.A.Gianturco
Caspur Supercomputing Centerand
University of Rome ”La Sapienza” URLS node of the EPIC Network
IntroductionIntroductionThe talk will be organized as follows:
Introduction to the e-molecule scattering theory based on the S.C.E. approach
SCELib(API)-VOLLOC code
Shape resonances analysis
Examples and possible applications
Conclusions and future perspectives
The Single Center Expansion method
Central field model :•Factorization of the wave-function in radial and angular components
•Bound and continuum electronic states of atoms
•Extension to bound molecular systems
•Electron molecule dynamics, molecular dynamics, surface science, biomodelling
The SCE method The SCE method
The Single Center Expansion method
( , , ) ( ) ( , )lm lmlm
F r F r Y
In the S.C.E. method we have a representation of the physical world based on a single point of reference so that any quantity involved can be written as
The SCE method The SCE method
The SCE method The SCE method
In the SCE method the bound state wavefunction of the target molecule is written as
1( ) ( ) ( , )k pk kk i hl hl
hl
x r u r X
The SCE method The SCE method
),(Υb),(Χ lmpkhlmm
pkhl
),(Sb),(Χ lmpkhlm
pkhl
l
lm
Symmetry adapted generalized harmonicsSymmetry adapted generalized harmonics
Symmetry adapted real spherical harmonicsSymmetry adapted real spherical harmonics
The SCE method The SCE method
)(cosP4π
1φ),(S l0
2
1
l0
)cosmφ(cosPm)!(l
m)!(l
2π
12l1)(φ),(S lm
2
1
mlm
Where S stays forWhere S stays for
)sinmφ(cosPm)!(l
m)!(l
2π
12l1)(φ),(S lm
2
1
mm-l
The bound orbitals are computed in a multicentre description using GTO basis functions of near-HF-limit quality - gk(a,rk)
The SCE method The SCE method
2krcba
jkjkj ezyx);c,b,a(N)r,(g
Where N is the normalization coefficient
2
1
cba2
3
j !!1c2!!1b2!!1a2
42N
2
0 0
( ) sin( ) ( ) ( , )k i i i kj kjhl lm lm kj v v j k
k j v lm
u r d b S C R d g r d
The quadrature is carried out using Gauss-Legendre abscissas and weights for and Gauss-Chebyshev abscissas and weights for , over a dicrete variable radial grid
The radial coefficients are computed by integration
The SCE method The SCE method
The SCE method The SCE method Once evaluated the radial coefficients each
bound one-electron M.O. is expanded as:
,Xrurru phl
hl
ihl
1i
So the one-electron density for a closed shell may beexpressed as
2
iiN2
2N21 |ru|2dx...dx|x,...,x,x|r
The SCE method The SCE method
and so we have the electron density as:
11 ( ) ( , )Ahlm hlmhlm
r r r X
then, from all of the relevantquantities are computed.
r
Where
drurudsin2r i
2
0
ii0
lm
The SCE method The SCE method
The Static Potential
N
i i
iSt
|Rr|
Zds|sr|
1srV
And as usual:
,XrVrV 1Alm
lm
Stlm
St
The SCE method The SCE method
Where :
dsr
rs
1l2
4rV
1l
lStlm
a
a
r
0
0
r1llm
lllm1l
drr
1rrdrrr
r
1
1l2
4
The SCE method The SCE method
The polarization potential:
rVrV corrcp
where rc is the cut-off radius
rVrV polcp
Short range interaction
Long range interaction
For r ≤ rc
For r > rc
Short-range first model:Free-Electron Gas Correlation Potential
1
0.0311ln 0.0584 0.00133 ln 0.0084 for 1.0
7 41/ 2
(1 )1 26 3
1/ 2 2
(1 )1 2
( ) ( , )
( )
r r r r rs s s s s
r rs s
r rs s
FEG AFEGcorr hlmhlmhlm
FEG
hlm
V r r X
r
V
V
for r 1.0s
with and =0.1423,1=1.0529,2=0.3334.
3 ( )4sr r
The SCE method The SCE method
Short-range second model:Ab-Initio Density Functional (DFT) Correlation Potential
where is the Correlation EnergycE
1( ) ( , )
( )
DFT ADFTcorr hlmhlmhlm
C
V r r X
E r
V
The SCE method The SCE method
Short-range second model:Ab-Initio Density Functional (DFT) Correlation Potential
21
22'1
2"1
21
22'1
2"1
1'1
3
5
F1'
1DFTcorr
G465GG372
ab
G423GG4
ab
G3
8GabCFFarV
32
2F
3
1
3
5
11
3
1
1
310
3C
cexprFrG
d1rF
We need to evaluate the first and second derivative of (r)In a general case we have:
The SCE method The SCE method
( , , ) ( ) ( , )lm lmlm
F r F r Y
lm
lmθlmlm
rlmlm
lmlmlm
eXsinθ
me
θ
X
r
FeX
dr
dF
θ,XrFθ,r,F
ˆˆˆ
We need to evaluate the first and second derivative of (r)In a general case we have:
The SCE method The SCE method
lm2
22
Xr
1ll
r
2
lm
lm2lm
2
lmlmlm
dr
dF
dr
Fd
θ,XrFθ,r,F
Problems with the radial part:
The SCE method The SCE method
Single center expansion of F,F’, and F” are time consuming
We performe a cubic spline of F to simplify the evaluation of
the first and second derivative
Problems with the angular part:
For large values of the angular momentum L it is possible toreach the limit of the double precision floating point arithmetic
To overcame this problem it is possible to use a quadrupole precision floating point arithmetic (64 bits computers)
The SCE method The SCE method Long-range :The asymptotic polarization potential
The polarization model potential is then corrected to take into account the long range behaviour
1l1l2
l
r
Apol r2
RlimR/rV 1
The SCE method The SCE method Long-range :The asymptotic polarization potential
zzyzxz
yzyyxy
xzxyxx
2
1
2
12
1
2
12
1
2
1
In the simple case of dipole-polarizability
av
av
av
00
00
00
The SCE method The SCE method Long-range :The asymptotic polarization potential
0
3
1
yzxzxy
zzyyxxavzzyyxxav
Where
cosPr2r2
V 242
40
pol
Usually in the case of a linear molecule one has
The SCE method The SCE method Long-range :The asymptotic polarization potential
Where
20zz20yyxx
22
2
1
1cos32
1cosP
The SCE method The SCE method Long-range :The asymptotic polarization potential
In a more general case
3,2,1j,iz,y,xq
qqr2
1z,y,xV
j.i
ij
3
1i
3
1jji6pol
Once evaluated the long range polarization potentialwe generate a matching function to link the short / long range part of Vpol
The exchange potential: first model The Free Electron Gas Exchange (FEGE) Potential
The SCE method The SCE method
Two great approximations: Molecular electrons are treated as in a free electron
gas, with a charge density determined by the ground electronic state
The impinging projectile is considered a plane wave
The SCE method The SCE method The exchange potential: first model The Free Electron Gas Exchange (FEGE) Potential
1/32( ) 3 ( )FK r r
1
2
( ) ( , )
2 1 1 1( ) ln
2 4 1
FEGE AFEGEhlmhlmhlm
F
V r r X
K r
V
/ Fk K
212Fpcoll rKIE2rk
The SCE method The SCE method
The exchange potential: second model The SemiClassical Exchange (SCE) Potential and modified SCE (MSCE)
SCE: The local momentum of bound electrons can be
disregarded with respect to that of the impinging projectile (good at high energy collisions)
2
1
s
2
s
2AST0
AST0
2SCE 8rVE
2
1rVE
2
1k,rV 11
The SCE method The SCE method
The exchange potential: second model The SemiClassical Exchange (SCE) Potential and modified SCE (MSCE)
MSCE: The local velocity of continuum particles is modified
by both the static potential and the local velocity of the bound electrons.
2
12
3
22A
ST03
22A
ST02
MSCE r4r310
3rVE
2
1r3
10
3rVE
2
1k,rV 11
The solution of the SCE coupled radial equations
Once the potentials are computed, one has to solve the integro-differential equation
2 2
*
1 1( ) ( )
2 2
1( ) ( ) ( )
k V r F r
u s F s dsu rr s
The SCE method The SCE method
The SCE method The SCE method
The solution of the SCE coupled radial equations
The quantum scattering equation single center expanded generate a set of coupling integro-differential equation
'h'l
p'h'l,lh'h'l,lh
,p'h'l,lh2
22
2
rfR/rVrfr
1llk
dr
d
The SCE method The SCE method
The solution of the SCE coupled radial equations
Where the potential coupling elements are given as:
r̂XR/rVr̂Xr̂d
r̂XR/rVr̂XR/rV
p'h'l
plh
p'h'l
plh
p'h'l,lh
The SCE method The SCE method The solution of the SCE coupled radial equations
The standard Green’s function technique allows us to rewritethe previous differential equations in an integral form:
n
r
0
pnjl
l'h'l,lhp
'h'l,lh
R/'rfR/'rV'r,rg'dr
krjR,rf
This equation is recognised as Volterra-type equation
The SCE method The SCE method
The solution of the SCE coupled radial equations
In terms of the S matrix one has:
jijj l
2
1kri
pij
l2
1krir
,pij eSerf
i,j identify the angular channel lh,l’h’
SCELib(API)-VOLLOC codeSCELib(API)-VOLLOC code
SCELIB-VOLLOC codeSCELIB-VOLLOC code
SCELIB-VOLLOC codeSCELIB-VOLLOC code
SCELIB-VOLLOC codeSCELIB-VOLLOC codeSerial / Parallel ( open MP / MPI )
SCELIB-VOLLOC codeSCELIB-VOLLOC code
Typical running time depends on:
Hardware / O.S. chosen Number of G.T.O. functions Radial / Angular grid size Number of atoms / electrons Maximum L value
SCELIB-VOLLOC codeSCELIB-VOLLOC code
Test cases:
SCELIB-VOLLOC codeSCELIB-VOLLOC code
Hardware tested:
Shape resonance analysis Shape resonance analysis
Shape resonance analysis Shape resonance analysis
2 1( ) ( ) ( ) tan2( )R R
R
E a b E E c E EE E
we fit the eigenphases sum with we fit the eigenphases sum with the the Briet-WignerBriet-Wigner formula and formula and evaluate evaluate and and
UracilUracil
UracilUracil
J.Chem.Phys., Vol.114, No.13, 2001
UracilUracil
• ER=9.07 eV R=0.38 eV =0.1257*10-15 s
UracilUracil
Thymine
J.Phys.Chem. A, Vol. 102, No.31, 1998
CubaneCubane
CubaneCubane
CubaneCubane
CubaneCubane
EErr=9.24 eV =9.24 eV =3.7 eV =3.7 eV =1.8*10=1.8*10-16-16ss
CubaneCubane
CubaneCubane
EErr=14.35 eV =14.35 eV =4.2 eV =4.2 eV =1.5*10=1.5*10-16-16ss
CubaneCubane
Conclusion and future Conclusion and future perspectivesperspectives
Shape resonance analysis (S-matrix poles)
Transient Negative Ion Orbitals analysis (post-SCF multi-det w/f)
Dissociative Attachment with charge migration seen through bond stretching ( (R) (R) )
Study of the other DNA bases (thymine t.b.p., A,C,G planned)
Development of new codes (SCELib-API & parallel VOLLOC)