Photochemistry: Photochemistry: adiabatic and nonadiabatic adiabatic and nonadiabatic molecular dynamics with  molecular dynamics with 

multireference ab initio methods  multireference ab initio methods 

Mario BarbattiMario Barbatti

Institute for Theoretical ChemistryUniversity of Vienna

COLUMBUS in BANGKOK (3-TSCOLUMBUS in BANGKOK (3-TS22CC22))Apr. 2 - 5, 2006Apr. 2 - 5, 2006

Burapha University, Bang Saen, ThailandBurapha University, Bang Saen, Thailand

OutlineOutline

First Lecture: An introduction to molecular dynamicsFirst Lecture: An introduction to molecular dynamics1. Dynamics, why?2. Overview of the available approaches

Second Lecture: Towards an implementation of surface hopping dynamicsSecond Lecture: Towards an implementation of surface hopping dynamics1. The NEWTON-X program 2. Practical aspects to be adressed

Third Lecture: Some applications: theory and experiment1. On the ambiguity of the experimental raw data 2. On how the initial surface can make difference3. Intersection? Which of them?4. Readressing the DNA/RNA bases problem

Part IIIPart IIISome applications:Some applications:

theory and experimenttheory and experiment

Cândido Portinari, Futebol, 1935

On the ambiguity of the On the ambiguity of the experimental raw dataexperimental raw data

Bonačić-Koutecký and Mitrić, Chem. Rev. 105, 11 (2005).

Experimental: pump-probeExperimental: pump-probeExperimental: pump-probeExperimental: pump-probe

Analysis of the experimental resultsAnalysis of the experimental resultsAnalysis of the experimental resultsAnalysis of the experimental results

Fuß et al., Faraday Discuss. 127, 23 (2004).

0 100 200 300 4000.0

0.2

0.4

0.6

0.8

1.0A

vera

ge

occ

up

atio

n

Time (fs)

SS11

SS22

SS00

Barbatti, Granucci, Persico and Lischka, CPL 401, 276 (2005)

The lifetime of ethyleneThe lifetime of ethyleneThe lifetime of ethyleneThe lifetime of ethylene

Method Lifetime (fs) DTSH [1] S1

S2,S0 139±1a / 105±1b DTSH [1] S1,S2

S0 188±2a / 137±2b DTSH [2] S1

S2,S0 50 AIMS [3] > 250 AIMS [4] 180 MCDTH [5] >> 100 Experimental [6] 30±15 Experimental [7] 20±10 Experimental (1 + 2) [8] 25±5

[1] Barbatti, Granucci, Persico and Lischka, CPL 401, 276 (2005).[2] Granucci, Persico, and Toniolo, JCP 114 (2001) 10608.[3] Ben-Nun and Martínez, CPL 298 (1998) 57.[4] Ben-Nun, Quenneville, and Martínez, JPCA 104 (2000) 5161.[5] Viel, Krawczyk, Manthe, Domcke, JCP 120 (2004) 11000. [6] Farmanara, Stert, and Radloff, CPL 288 (1998) 518.[7] Mestagh, Visticot, Elhanine, Soep, JCP 113 (2000) 237.[8] Stert, Lippert, Ritze, and Radloff, CPL 388 (2004) 144.

a Evb = 6.2 ± 0.3 eV.

b Evc = 7.4 ± 0.15 eV.

Survey of theoretical and experimental predictionsSurvey of theoretical and experimental predictionsSurvey of theoretical and experimental predictionsSurvey of theoretical and experimental predictions

Eion-Epot

S0

S1

C2H4+

MXS

0 20 40 60 80 100 120 140 160 180 2002

4

6

8

bc

172 nm (7.21 eV)

nd

267 nm (4.6 eV)Eio

n-E

pot (

eV)

Time (fs)

Ev = 6.2 eV

Ev = 7.4 eV

Radloff has a rather distinct explanation!CPL 388 (2004) 144.

The time-window questionThe time-window questionThe time-window questionThe time-window question

On how the initial surface On how the initial surface can make differencecan make difference

0

2

4

6

8

10

12

14

1.2

1.3

1.4

1.5

1.6

015

3045

6075

90

Ene

rgy

(eV

)

CN

Stre

tch

(Å)

Torsion (°)

Basic scenery expected:Torsion + decay at twisted MXS

CNHCNH44++: MRCI/CAS(4,3)/6-31G*: MRCI/CAS(4,3)/6-31G*CNHCNH44

++: MRCI/CAS(4,3)/6-31G*: MRCI/CAS(4,3)/6-31G*

This and other movies are available at:homepage.univie.ac.at/mario.barbatti

Barbatti, Aquino and Lischka, Mol. Phys. in press (2005)

0

2

4

6

8

10

12

14

1.2

1.3

1.4

1.5

1.6

015

3045

6075

90

Ene

rgy

(eV

)

CN

Stre

tch

(Å)

Torsion (°)

Large momentum along CN stretch isacquired in the S2-S1 transition.

Stretching + pyramidalization dominate

CNHCNH44++: MRCI/CAS(4,3)/6-31G*: MRCI/CAS(4,3)/6-31G*CNHCNH44

++: MRCI/CAS(4,3)/6-31G*: MRCI/CAS(4,3)/6-31G*

0

2

4

6

8

10

12

14

1.2

1.3

1.4

1.5

1.6

015

3045

6075

90

Ene

rgy

(eV

)

CN

Stre

tch

(Å)

Torsion (°)

If S1 (*) is directly populated,the torsion should dominate thedynamics.

CNHCNH44++: MRCI/CAS(4,3)/6-31G*: MRCI/CAS(4,3)/6-31G*CNHCNH44

++: MRCI/CAS(4,3)/6-31G*: MRCI/CAS(4,3)/6-31G*

This and other movies are available at:homepage.univie.ac.at/mario.barbatti

Intersection? Intersection? Which of them?Which of them?

The SThe S00/S/S11 crossing seam crossing seamThe SThe S00/S/S11 crossing seam crossing seam

4

5

6

7

8

-100

-50

0

50

100

4060

80100

120

Ene

rgy

(eV

)

(degre

es)

degrees)

EthylideneEthylidene

PyramidalizedPyramidalized

H-migrationH-migration

Barbatti, Paier and Lischka, JCP 121, 11614 (2004).

Ohmine 1985Freund and Klessinger 1998Ben-Nun and Martinez 1998Laino and Passerone 2004

CC3V3V

Evolution on the configuration spaceEvolution on the configuration spaceEvolution on the configuration spaceEvolution on the configuration space

20 40 60 80 100 120 140

0

10

20

30

0

10

20

30

0

10

20

30

Hydrogen Migration (degrees)

Twisted

planar

Pyr

amid

aliz

atio

n (d

egre

es)

Ethylid. MXS

Pyramid. MXS

H-mig. c.i.

First S1S0 hopping.

Torsion Torsion + Pyramid.+ Pyramid.

H-migrationH-migration

Pyram. MXSPyram. MXS

Ethylidene MXSEthylidene MXS

~7.6 eV~7.6 eV

~ 100-140 fs~ 100-140 fs

60%60%

11%11%23%23%

Barbatti, Ruckenbauer and Lischka, JCP 122, 174307 (2005)

Conical intersections in ethyleneConical intersections in ethyleneConical intersections in ethyleneConical intersections in ethylene

Readressing the Readressing the DNA/RNA bases problemDNA/RNA bases problem

Why RNA and DNA are composed by only 5 bases?

Ultrafast deactivation might have played a role in natural selection of them.

Ultrafast deactivation means more stability against photoinduced damage.

In water = 0.72 psN

N

NH

N

NH2

= 1.1 psN

C

C

N

C

C

NH2

O

H

H

H

N

N

NH

N

NH2

= 30 ps

Canuel et al. JCP 122, 074316 (2005)

In water = 73 ps

Blancafort et al. JPCA 109, 4431 (2005)

N

C

C

N

C

C

NH2

O

F

H

H

Deactivation in early biotic agesDeactivation in early biotic agesDeactivation in early biotic agesDeactivation in early biotic ages

Is the ultrafast deactivation important for the photostability of DNA/RNA?

Schultz et al., Science 306, 1765 (2004)

In this model, proton transfer along the nitrogen bonds between bases is responsible for internal conversion.

Base pairs, base stacks: alternative modelsBase pairs, base stacks: alternative modelsBase pairs, base stacks: alternative modelsBase pairs, base stacks: alternative models

Crespo-Hernández, Cohen & Kohler, Nature 436, 1141 (2005)

In this other model, base-stack interactions lead to ultrafast formation of excimers

The defects stay localized in the excimers and can be fixed by using the second strand as a template

Base pairs, base stacks: alternative modelsBase pairs, base stacks: alternative modelsBase pairs, base stacks: alternative modelsBase pairs, base stacks: alternative models

Base–pairs and base stack models depend on the presence of a second strand to explain the photostability.

But RNA is normally single-stranded. Therefore, both models doesn't explain it completely.

Moreover, RNA appeared in Nature before DNA. So some molecular processes promoting photostability must be based on single-stranded systems and, maybe, isolated bases.

Probably, the photostability of NAs is due to several levels of mechanisms, since ultrafast deactivation of isolated bases to enzymatic repair.

Base pairs, base stacks: what they cannot explainBase pairs, base stacks: what they cannot explainBase pairs, base stacks: what they cannot explainBase pairs, base stacks: what they cannot explain

““[Darwinism] is a breathtaking cascade of levels upon levels upon levels, [Darwinism] is a breathtaking cascade of levels upon levels upon levels, with new principles of explanation, new phenomena appearing at each with new principles of explanation, new phenomena appearing at each level, forever revealing that the fond hope of explaining ‘everything’ at level, forever revealing that the fond hope of explaining ‘everything’ at some one lower level is misguided.”some one lower level is misguided.”

Daniel Dennett, Darwin’s Dangerous Idea, p. 195Daniel Dennett, Darwin’s Dangerous Idea, p. 195

The adenine`s deactivation:The adenine`s deactivation:aminopyrimidine as a model for adenineaminopyrimidine as a model for adenine

An example: photodynamics of DNA/RNA basesAn example: photodynamics of DNA/RNA basesAn example: photodynamics of DNA/RNA basesAn example: photodynamics of DNA/RNA bases

What has theory to say?

For adenine • The decay can be due to */S0 crossing (N9-H stretching)

• Or maybe due to the */S0 crossing (C2-H puckering)

• Or n*/S0 crossing, who knows (NH2 out-of-plane)?

• Maybe, there’s no crossing at all!

Experimental lifetimes of the excited state of DNA/RNA bases: ~ 1 ps

5

4

6

N3

N1

2 N6

8

7

N10

H

H

H

HH

N

N

N

H

HH

H

H

N

N

N

N

H

H

HHthymine(uracil)

deoxyribose(ribose)

a) 9H-adenine b) 6-aminopyrimidine

c)

Adenine is still too big to be studied by adequate ab initio dynamics methods.

The 6-aminopyrimidine (6AMP) may help to understand the nature and efficiency of the C2H puckering and out-of-plane NH2.

Some partial information about the role of the imidazole group can be added to the model by isotopic substitutions at H4 and H5.

MotivationMotivationMotivationMotivation

Min S0 Min S1 CI 21 MXS 10

0

1

2

3

4

5

6

7

Min S0 Min S1 CI 21 MXS 10

0

1

2

3

4

5

6

7

n*/*

Reaction Path

*

n*

*

*

n*/*

planar relaxation out-of-plane NH2

236 nm

236 nm

n*/*

Ene

rgy

(eV

)

S2

S1

S0

*

n*

*

*n*/*

AMP: SA-3-CAS(8,7)/6-31G*

planar relaxation out-of-plane C2H

The basic features of adenine`s PES are present in 6AMP.

The reaction pathsThe reaction pathsThe reaction pathsThe reaction paths

0 100 200 300 4000

1

2

3

4

5

6

7

8

9

10

En

erg

y (e

V)

Time (fs)

current state

The dynamics of 6AMP: preferential pathThe dynamics of 6AMP: preferential pathThe dynamics of 6AMP: preferential pathThe dynamics of 6AMP: preferential path

45 a.m.u.

45 a.m.u.

Preliminary results show a substantial increase in the lifetime of substituted 6AMP in comparison to normal 6AMP

The dynamics of 6AMP: isotopic effectThe dynamics of 6AMP: isotopic effectThe dynamics of 6AMP: isotopic effectThe dynamics of 6AMP: isotopic effect

The dynamics of 6AMPThe dynamics of 6AMPThe dynamics of 6AMPThe dynamics of 6AMP

0 200 400 600 800 10000

1

2

3

4

5

6

7

8

9E

ne

rgy

(eV

)

Time (fs)

current state

The dynamics of 6AMPThe dynamics of 6AMPThe dynamics of 6AMPThe dynamics of 6AMP

• NH2 out-of-plane path is never activated

• In normal 6AMP, C4H-puckering is the dominant path. S1 lifetime is 400 fs.

• In the substituted species, out-of-plane deformations involving C6H and N3 are the preferential path. S1 lifetime is 800 fs.

We expect a similar scenario in the case of adenine:We expect a similar scenario in the case of adenine:Out-of-plane deformation of COut-of-plane deformation of C22H and NH and N33 sites and no sites and no

contribution of the out-of-plane NHcontribution of the out-of-plane NH22 conical intersections. conical intersections.

ConclusionsConclusions

ConclusionsConclusionsConclusionsConclusions

Dynamics, Why?• Ab initio dynamics can be used to characterize lifetimes, and relaxation paths in the ground and excited state, occurring in the time scale of sub-picosecond.• Dynamics reveal features that are not easily found by static methods.• Dynamics can be used to locate the important regions of the crossing seam.

Dynamics, what kind?• Semiclassical dynamics:

• Cheap. • Good results if nuclear non-local phenomena are not important.• No information about quantization of rotational and vibrational modes.

• Wave packet: • Expensive. • Full and reliable quantum results. • Limited to few degrees of freedom.

ConclusionsConclusionsConclusionsConclusions

Excited-state dynamics around the world (a very incomplete and biased inventory…)• Semiclassical dynamics:Tully; Jasper and Thrular; Robb, Olivucci and Buss; Barbatti and Lischka; Marx and Doltsinis (Car-Parrinelo); Granucci and Persico (local diabatization); Martinez-Nuñez; Pittner and Bonačić-Koutecký; Neufeld.

•Multiple spawningBen-Nun and Martínez

• Wave packetGonzalez and Manz; Manthe and Cederbaum; Viel, Eisfeld and Domcke; Jacubtz; de Vivie-Riedle and Hofmann; Schinke; Köppel.

Our contributionOur contributionOur contributionOur contribution

Towards an implementation of surface hopping dynamics• NEWTON-X: new implementation of on-the-fly surface hopping dynamics.• Energies, gradients and nonadiabatic coupling vectors can be read from any quantum chemical package.• For MRCI and CASSCF dynamics, COLUMBUS has been used.• For TD-DFT and RI-CC2, TURBOMOLE.

Where are we going now?• QM/MM: investigation of the influence of the environment on the relaxation paths, lifetimes and efficiency of the crossing seam (COLUMBUS + TINKER).

MRCI, CAS

Force field

CollaboratorsCollaboratorsCollaboratorsCollaborators

Vienna:Hans LischkaAdélia AquinoMatthias RuckenbauerGunther ZechmannAlejandro Lopez-Castillo

Pisa:Giovanni Granucci

Prague:Jiri Pittner

Zagreb:Mario Vazdar

Vienna, March 2006Vienna, March 2006

SupportSupportSupportSupport

This work has been funded by: This work has been funded by: • Austrian Science Fund within the Special Research Program F16 Austrian Science Fund within the Special Research Program F16 (Advanced Light Sources)(Advanced Light Sources)• COST-Chemistry, Project No. D26-0006-02. COST-Chemistry, Project No. D26-0006-02. • Brazilian agency CNPqBrazilian agency CNPq• Calculations have been partially performed at Schroedinger III cluster of Calculations have been partially performed at Schroedinger III cluster of University of Vienna.University of Vienna.

Special thanks to: Special thanks to: • Prof. Vudichai ParasukProf. Vudichai Parasuk• Prof. Supot Hannongbua Prof. Supot Hannongbua • Dr. Suchaya PongsaiDr. Suchaya Pongsai• Burapha and Chulalongkorn UniversitiesBurapha and Chulalongkorn Universities

Cândido Portinari, Dom Quixote, 1956