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