Towards PPCC
So HirataQuantum Theory Project
University of Florida
Sanibel Symposium 2008, Parallel CC Workshop
Issues at petascale Increased complexity of algorithms and
implementations – computerized derivation and implementation / optimization, portability, extensibility, maintainability / parallel middleware
Multilevel hierarchical parallelism – hierarchical structures of chemical computing / linear scaling, PES scan, ab initio MD/MC
Fault tolerance, restart capability, calculation log, and verification – parallel middleware / compartmentation of calculations / redundant calculations / hierarchical methods
Automated symbolic algebraHirata, JPCA (2003); Hirata, TCA (2006); Hirata, JP Conf. Ser. (2006)
Definition of a many-electron theory 0 1 2 0 1 2 0 1 2 0exp ; 0 exp ; 0 expa ab
i ijC C CE H T T H T T H T T
Mathematical expressions
A parallel computer program
Automated symbolic algebraHirata, JPCA (2003); Hirata, TCA (2006); Hirata, JP Conf. Ser. (2006)
Agent Smith“The Matrix”
Correct scaling by factorized, reusable intermediates
Spin, point-group, and permutation symmetries
Dynamic load balancing parallelism; scalable
Runtime adjustment of memory usage
Never send a human to do a machine’s job
Implemented methodsHirata JPCA (2003); Hirata TCA (2006); Hirata JP Conf Ser (2006)
CI
PTCC Combined CC+PT
CCSD(T)CCSD(2)T, CCSD(3)T
CCSD(2)TQ, CCSD(3)TQ
CCSDT(2)Q, CR-CCSD(T)Hirata et al. JCP (2004)
Shiozaki, Hirao & Hirata JCP (2007)
Linear ExpansionCIS, CISD, CISDT, CISDTQ
Hirata JPCA (2003)
CIS+perturbationCIS(D), CIS(3), CIS(4)
Hirata JCP (2005)
PerturbationMP2, MP3, MP4
Hirata JPCA (2003)
Excited State TheoriesEOM-CCSD
EOM-CCSDTEOM-CCSDTQ
Hirata JCP (2004)
Ionization TheoryIP-EOM-CCSD
IP-EOM-CCSDTIP-EOM-CCSDTQKamiya & Hirata JCP (2006)
Cluster ExpansionCCD, CCSD, CCSDT,
CCSDTQ, LCCD,LCCSD, QCISD
Hirata JPCA (2003)
Electron Attachment TheoryEA-EOM-CCSD
EA-EOM-CCSDTEA-EOM-CCSDTQ
Kamiya & Hirata (2007)
EOM-CC+perturbationEOM-CCSD(2)T, EOM-CCSD(2)TQ
EOM-CCSD(3)TShiozaki, Hirao & Hirata JCP (2007)
Other CIS+2nd orderD-CIS(2), SCS-CIS(D)
SOS-CIS(D)Fan & Hirata (2007)
CC-R12, EOM-CC-R12, Λ-CC-R12Shiozaki, Kamiya, Hirata, & Valeev, in preparation (2008)
Toru ShiozakiUniversity of Florida
New types of ansatz – new symbolic algabra codeSignificantly more complex equationsLonger computational sequencesMultiple hotspotsPossibilities of various approximations
CC-R12
R12-CCSD on 100 processors ~ CCSD on 100,000 processors
Linear scaling CC
Linear scaling CCSD on 1 processor ~ CCSD on 100,000 processors
Fast methods for water clustersHirata et al. MP (2005)
n n
ij i j ii j i
E E E E E
Pair energy in the presence of dipole field
N-body (N > 2) Coulomb in dipole-dipole approximation
1 and 2-bodyCoulombExchangeCorrelation
Fast methods: excited statesHirata et al. MP (2005)
A record EOM-CCSD aug-cc-pVDZ calculation for a 247-atom system
0 5 10 15 20
Number of monomer units
CP
U t
ime
(arb
itrar
y un
its)
Conventional
Pair interaction (no cutoff)
Pair interaction (cutoff at 30 bohr)
Constant scaling!
Coupled-cluster for solids
Maddox (Nature, 1988): “One of the continuing scandals in the physical sciences is that it remains in general impossible to predict the structure of even the simplest crystalline solids from a knowledge of their chemical composition. … Solids such as crystalline water (ice) are still thought to lie beyond mortals’ ken.”
1 and 2 type solid formic acid
Molecular crystals
Ice XI
Formamide
Hydrogen fluoride
