PMID- 18412435
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20080619
LR  - 20080416
IS  - 0021-9606 (Print)
IS  - 0021-9606 (Linking)
VI  - 128
IP  - 14
DP  - 2008 Apr 14
TI  - Partially linearized, fully size-extensive, and reduced multireference 
      coupled-cluster methods. II. Applications and performance.
PG  - 144119
LID - 10.1063/1.2868768 [doi]
AB  - The partially linearized (pl), fully size-extensive multireference (MR) 
      coupled-cluster (CC) method, fully accounting for singles (S) and doubles (D) and 
      approximately for a subset of primary higher than doubles, referred to as plMR 
      CCSD, as well as its plMR CCSD(T) version corrected for secondary triples, as 
      described in Part I of this paper [X. Li and J. Paldus, J. Chem. Phys. 128, 
      144118 (2008)], are applied to the problem of bond breaking in the HF, F2, H2O, 
      and N2 molecules, as well as to the H4 model, using basis sets of a DZ or a 
      cc-pVDZ quality that enable a comparison with the full configuration interaction 
      (FCI) exact energies for a given ab initio model. A comparison of the performance 
      of the plMR CCSD/CCSD(T) approaches with those of the reduced MR (RMR) 
      CCSD/CCSD(T) methods, as well as with the standard single reference (SR) CCSD and 
      CCSD(T) methods, is made in each case. For the H4 model and N2 we also compare 
      our results with the completely renormalized (CR) CC(2,3) method [P. Piecuch and 
      M. Wloch, J. Chem. Phys. 123, 224105 (2005)]. An important role of a proper 
      choice of the model space for the MR-type methods is also addressed. The 
      advantages and shortcomings of all these methods are pointed out and discussed, 
      as well as their size-extensivity characteristics, in which case we distinguish 
      supersystems involving noninteracting SR and MR subsystems from those involving 
      only MR-type subsystems. Although the plMR-type approaches render fully 
      size-extensive results, while the RMR CCSD may slightly violate this property, 
      the latter method yields invariably superior results to the plMR CCSD ones and is 
      more easy to apply in highly demanding cases, such as the triple-bond breaking in 
      the nitrogen molecule.
FAU - Li, Xiangzhu
AU  - Li X
AD  - Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario N2L 
      3G1, Canada. xli@scienide.uwaterloo.ca
FAU - Paldus, Josef
AU  - Paldus J
LA  - eng
PT  - Journal Article
PL  - United States
TA  - J Chem Phys
JT  - The Journal of chemical physics
JID - 0375360
EDAT- 2008/04/17 09:00
MHDA- 2008/04/17 09:01
CRDT- 2008/04/17 09:00
PHST- 2008/04/17 09:00 [pubmed]
PHST- 2008/04/17 09:01 [medline]
PHST- 2008/04/17 09:00 [entrez]
AID - 10.1063/1.2868768 [doi]
PST - ppublish
SO  - J Chem Phys. 2008 Apr 14;128(14):144119. doi: 10.1063/1.2868768.