Imperial College London
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Professor Peter Haynes

Central Faculty, Office of the Provost

Vice-Provost (Education and Student Experience)
 
 
 
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Contact

 

p.haynes Website

 
 
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Assistant

 

Mrs Anushka Patel +44 (0)20 7594 6070

 
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Location

 

409Faculty BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Zuehlsdorff:2015:10.1063/1.4936280,
author = {Zuehlsdorff, TJ and Hine, NDM and Payne, MC and Haynes, PD},
doi = {10.1063/1.4936280},
journal = {Journal of Chemical Physics},
pages = {1--13},
title = {Linear-scaling time-dependent density-functional theory beyond the Tamm-Dancoff approximation: obtaining efficiency and accuracy with in situ optimised local orbitals},
url = {http://dx.doi.org/10.1063/1.4936280},
volume = {143},
year = {2015}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - We present a solution of the full time-dependent density-functional theory (TDDFT) eigenvalue equation in the linear response formalism exhibiting a linear-scaling computational complexity with system size, without relying on the simplifying Tamm-Dancoff approximation (TDA). The implementation relies on representing the occupied and unoccupied subspaces with two different sets of in situ optimised localised functions, yielding a very compact and efficient representation of the transition density matrix of the excitation with the accuracy associated with a systematic basis set. The TDDFT eigenvalue equation is solved using a preconditioned conjugate gradient algorithm that is very memory-efficient. The algorithm is validated on a small test molecule and a good agreement with results obtained from standard quantum chemistry packages is found, with the preconditioner yielding a significant improvement in convergence rates. The method developed in this work is then used to reproduce experimental results of the absorption spectrum of bacteriochlorophyll in an organic solvent, where it is demonstrated that the TDA fails to reproduce the main features of the low energy spectrum, while the full TDDFT equation yields results in good qualitative agreement with experimental data. Furthermore, the need for explicitly including parts of the solvent into the TDDFT calculations is highlighted, making the treatment of large system sizes necessary that are well within reach of the capabilities of the algorithm introduced here. Finally, the linear-scaling properties of the algorithm are demonstrated by computing the lowest excitation energy of bacteriochlorophyll in solution. The largest systems considered in this work are of the same order of magnitude as a variety of widely studied pigment-protein complexes, opening up the possibility of studying their properties without having to resort to any semiclassical approximations to parts of the protein environment.
AU  - Zuehlsdorff,TJ
AU  - Hine,NDM
AU  - Payne,MC
AU  - Haynes,PD
DO  - 10.1063/1.4936280
EP  - 13
PY  - 2015///
SN  - 0021-9606
SP  - 1
TI  - Linear-scaling time-dependent density-functional theory beyond the Tamm-Dancoff approximation: obtaining efficiency and accuracy with in situ optimised local orbitals
T2  - Journal of Chemical Physics
UR  - http://dx.doi.org/10.1063/1.4936280
UR  - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000366319700009&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - https://aip.scitation.org/doi/10.1063/1.4936280
UR  - http://hdl.handle.net/10044/1/28714
VL  - 143
ER  -
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