PMID- 26593652
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20151124
LR  - 20151123
IS  - 1549-9618 (Print)
IS  - 1549-9618 (Linking)
VI  - 8
IP  - 5
DP  - 2012 May 8
TI  - Accelerating the Convergence and Reducing the Variance of Path Integral 
      Calculations of Quantum Mechanical Free Energies by Using Local Reference 
      Potentials.
PG  - 1589-96
LID - 10.1021/ct300098p [doi]
AB  - We present two new methods to accelerate the convergence of Feynman path integral 
      calculations of thermodynamic partition functions. The first enhancement uses 
      information from instantaneous normal mode (INM) calculations to decrease the 
      number of discretized points necessary to represent the Feynman paths and is 
      denoted the local generalized Pitzer-Gwinn (LGPG) scheme. The second enhancement, 
      denoted harmonically guided variance reduction (HGVR), reduces the variance in 
      Monte Carlo (MC) calculations by exploiting the correlation between the sampling 
      error associated with the sum over paths at a particular centroid location for 
      the accurate potential and for the INM approximation of a model potential, the 
      latter of which can be exactly calculated. The LGPG scheme can reduce the number 
      of quadrature points required along the paths by nearly an order of magnitude, 
      and the HGVR scheme can reduce the number of MC samples needed to achieve a 
      target accuracy by more than an order of magnitude. Numerical calculations are 
      presented for H2O2, a very anharmonic system where torsional motion is important, 
      and H2O, a system more amenable to harmonic reference treatment.
FAU - Mielke, Steven L
AU  - Mielke SL
AD  - Department of Chemistry and Supercomputing Institute, University of Minnesota , 
      207 Pleasant St. S.E., Minneapolis, Minnesota 55455-0431, United States.
FAU - Truhlar, Donald G
AU  - Truhlar DG
AD  - Department of Chemistry and Supercomputing Institute, University of Minnesota , 
      207 Pleasant St. S.E., Minneapolis, Minnesota 55455-0431, United States.
LA  - eng
PT  - Journal Article
DEP - 20120405
PL  - United States
TA  - J Chem Theory Comput
JT  - Journal of chemical theory and computation
JID - 101232704
EDAT- 2012/05/08 00:00
MHDA- 2012/05/08 00:01
CRDT- 2015/11/24 06:00
PHST- 2015/11/24 06:00 [entrez]
PHST- 2012/05/08 00:00 [pubmed]
PHST- 2012/05/08 00:01 [medline]
AID - 10.1021/ct300098p [doi]
PST - ppublish
SO  - J Chem Theory Comput. 2012 May 8;8(5):1589-96. doi: 10.1021/ct300098p. Epub 2012 
      Apr 5.