PMID- 26574467
OWN - NLM
STAT- MEDLINE
DCOM- 20160909
LR  - 20151117
IS  - 1549-9626 (Electronic)
IS  - 1549-9618 (Linking)
VI  - 11
IP  - 8
DP  - 2015 Aug 11
TI  - Spins Dynamics in a Dissipative Environment: Hierarchal Equations of Motion 
      Approach Using a Graphics Processing Unit (GPU).
PG  - 3859-65
LID - 10.1021/acs.jctc.5b00488 [doi]
AB  - A system with many energy states coupled to a harmonic oscillator bath is 
      considered. To study quantum non-Markovian system-bath dynamics numerically 
      rigorously and nonperturbatively, we developed a computer code for the reduced 
      hierarchy equations of motion (HEOM) for a graphics processor unit (GPU) that can 
      treat the system as large as 4096 energy states. The code employs a Pade spectrum 
      decomposition (PSD) for a construction of HEOM and the exponential integrators. 
      Dynamics of a quantum spin glass system are studied by calculating the free 
      induction decay signal for the cases of 3 x 2 to 3 x 4 triangular lattices with 
      antiferromagnetic interactions. We found that spins relax faster at lower 
      temperature due to transitions through a quantum coherent state, as represented 
      by the off-diagonal elements of the reduced density matrix, while it has been 
      known that the spins relax slower due to suppression of thermal activation in a 
      classical case. The decay of the spins are qualitatively similar regardless of 
      the lattice sizes. The pathway of spin relaxation is analyzed under a sudden 
      temperature drop condition. The Compute Unified Device Architecture (CUDA) based 
      source code used in the present calculations is provided as Supporting 
      Information .
FAU - Tsuchimoto, Masashi
AU  - Tsuchimoto M
AD  - Department of Chemistry, Graduate School of Science, Kyoto University , Sakyoku, 
      Kyoto 606-8502, Japan.
FAU - Tanimura, Yoshitaka
AU  - Tanimura Y
AD  - Department of Chemistry, Graduate School of Science, Kyoto University , Sakyoku, 
      Kyoto 606-8502, Japan.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Chem Theory Comput
JT  - Journal of chemical theory and computation
JID - 101232704
SB  - IM
MH  - *Algorithms
MH  - *Quantum Theory
MH  - Temperature
EDAT- 2015/11/18 06:00
MHDA- 2016/09/10 06:00
CRDT- 2015/11/18 06:00
PHST- 2015/11/18 06:00 [entrez]
PHST- 2015/11/18 06:00 [pubmed]
PHST- 2016/09/10 06:00 [medline]
AID - 10.1021/acs.jctc.5b00488 [doi]
PST - ppublish
SO  - J Chem Theory Comput. 2015 Aug 11;11(8):3859-65. doi: 10.1021/acs.jctc.5b00488.