gpu computation
TRANSCRIPT
Efficient simulation of quantum dynamics system using GPU
Lipeng Chen
Division of Materials Science
Nanyang Technological University, Singapore
Schrodinger Equation Liouville equation
1. MCTDH
2. propagator
1. QUAPI
2. HEOM
Exciton diffusion in chlorosome antennas
Single molecule spectra
Dissipative effect on the dynamics at a conical intersection
Polaron dynamics of Holstein model
Dynamics of sub-Ohmic spin boson model
Natural Light Harvesting Complexes
Fenna-Matthews-Olson (FMO)Trimer complex in green sulfur bacteria 4
Light harvesting system in purple bacteriaLHCII in green plants
Chlorosomes antennas in green sulfur bacteria
5
Exciton diffusion in chlorosomes antennas
6S. Ganapathy et al, PNAS. 2009, 106 , 8525
Variational Parameters
7
Quantum state of the system can be approximated, by the Davydov D1 Ansatz
SchrÖdinger Equation
Dirac-Frenkel time-dependent variational method
Equations of motion for the variational parameters
( ) ( )i t H tt
( ) ( )2iL t H t
t
�
( ) 0m
m
d L Ldt
SMX: Higher performance and efficiency increase processing cores reduce control logic
Dynamic parallelism: spawns new threads without going back to the CPU
Hyper-Q: increases GPU utilization provide streams access to 32 independent hardware work queues or MPI ranks.
KEPLER - The World‘s fastest, most efficient HPC architecture
30 rings of 18 sites each540 sites in total
Phonon bandwidth: W=0.5Coupling: g=0.4
18 rings with 18 site each (324 sites)
Coherence size: 175 sites
1
( )
,
20
( ) ( , ) 0 0
( )( ) [coth (1 cos ) (sin )]2
0 ( )
S
S
H tg tph ph
n m
B
iH tph D
R t e C n m n e m
Dg t d t i t tk T
e n t
Single molecule spectra
R Hildner, D Brinks, J. B. Nieder, R. J. Cogdell, N F van Hulst, Science 340, 1448 (2013)
Ultrafast phase coherent excitation of individual LH2 complexes
Emission of single LH2 complexes as a function of delay time
Histogram of the oscillation period T
Single molecule spectra
1
2
†
1 2
1
( )2
[ ( ) ( ) ]( ) ( ) ( )
( ) ( )
( ) ( )
F
i t
i t
H t X t Xt t t
t E t e
t E t e
Field-matter interaction Hamiltonian
Liouville Equation
( ) [ , ]Fd t i H Hdt
( ) { ( )}
( ) 2 ( ) ( )
P t Tr X t
S Im dt t P t
2
1
( ) ( )kk
k
S S
2
1, 1
1 1 10
( )
,
20
( ) ( )
2Re ( ) ( ) ( )
( ) ( , ) 0 0
( )( ) [coth (1 cos ) (sin )]2
S
aba b
ab a b
H tg tph ph
n m
B
S
dt dt t t t R t
R t e C n m n e m
Dg t d t i t tk T
1
1
†
0 ( )
( ) ( ) exp [ ( ) . .] 0
SiH tph D
D n nq q phn q
e n t
t t n t b H c
D1 dynamics
1 1( ) ( ) ( )
2
( ) 0
( ) 0
D S D
nn
nqnq
iL t H tt t
d L Ldt
d L Ldt
� � � � � � � � � � � � � �
Pump pulse 1Pump pulse 2
Signal
Room temperature LHCII absorption spectra
Single molecule signal for 3 values of the exciton-phononcoupling strength (decreasing)
same signals but calculated without the heat bath
the effect of the single molecule orientation The effect of disorder
Effect of a dissipative environment on the dynamics at a conical intersection
Polaron dynamics of Holstein model
J: transfer integralN: number of sitesϕ : off-diagonal couplingg: diagonal couplingW: phonon band width
A linear dispersion phonon band is assumed as
0
21 1q
qW
Multitude of Davydov D1 and D2 trial states
1D t 2D t
† †2 ,
0
0 ( )exp 0M
Mn i n iq q iq qex ph
n i q
D a t b b
† †1 ,
0
0 ( )exp 0M
Mn i n inq q inq qex ph
n i q
D a t b b
Multi-D2 and multi-D1 Ansatz with the multiplicity number M
Measurement of the validity for the trial state
1,2( ) ( )
Mtt i H D
t t t
Multi-D1 results in the diagonal coupling case
Case of J=0.5. W=0.5, g=0.1 and ϕ=0
Multi-D2 results in the diagonal coupling case
In the off-diagonal coupling case with g=W=J=0 and ϕ≠0
1,2( ) ( )
( )=max ( )
Mt
ph
t i H D
t t t
tE t
Reduced density matrix
Feynman-Vernon influence functional
HEOM treatment of Holstein model
Auxiliary density matrix
1
N
q trunq
m N
Terminator
Ntrun
N
3 4 5 6 7 8 9 10
6 455 1820 6188 18564 50388 125970 293930
8 969 4845 20349 74613 245157 735471
9 1330 7315 33649 134596
10 1771 10626 53130 230230
12 2925 20475 118750 593770
16 6545 58905 435897
Total number of hierarchy
1 !! 1 !
trun trun
trun
N N NN N N
0.2, 0.5, 0.1, 0J W g
0.5, 0.5, 0.1, 0J W g
0.2, 0.5, 0.2, 0J W g
0.5, 0.5, 0.2, 0J W g
Dynamics of sub-Ohmic spin-boson model
Δ: the tunneling constantε: the spin bias λl: the coupling strength of the spin to the bath
Multi-D1 results v.s D1 results Sub-Ohmic bath s=0.25 Δ=0.1 Relative error
Multi-D1 compare with HEOM
Factorized initial condition bath
Multi-D1 compare with HEOM
Factorized initial condition bath
Multi-D1 compare with PIMC
Polarized initial condition bath
Entropy of the system
Factorized initial condition
Some useful libraries