Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Illustration of a TDDFT spatial overlap diagnostic by basis function exponent scaling
AU - Peach, Michael J. G.
AU - Tozer, David J.
PY - 2009/11/30
Y1 - 2009/11/30
N2 - The relationship between TDDFT vertical excitation energy accuracy and the degree of occupied-virtual spatial orbital overlap is investigated for the CO molecule, by systematically controlling the overlap through a scaling of the basis function exponents. Increasing the scaling parameter contracts the basis set, increasing the overlap values. The corresponding excitation energies also increase and become more accurate, relative to approximate second-order coupled cluster values determined using the same, scaled basis. For the 36 data points (four excitations, each evaluated using nine exponent scaling parameters) there is a strong correlation between excitation energy accuracy and orbital overlap with a generalised gradient approximation functional. Similar correlation is observed with a hybrid and Coulomb-attenuated functional, but the errors become progressively smaller due to their increased fraction of exact, non-local exchange at long-range. The results are fully consistent with the diagnostic test of J. Chem. Phys. 128 (2008) 044118. (C) 2009 Elsevier B.V. All rights reserved.
AB - The relationship between TDDFT vertical excitation energy accuracy and the degree of occupied-virtual spatial orbital overlap is investigated for the CO molecule, by systematically controlling the overlap through a scaling of the basis function exponents. Increasing the scaling parameter contracts the basis set, increasing the overlap values. The corresponding excitation energies also increase and become more accurate, relative to approximate second-order coupled cluster values determined using the same, scaled basis. For the 36 data points (four excitations, each evaluated using nine exponent scaling parameters) there is a strong correlation between excitation energy accuracy and orbital overlap with a generalised gradient approximation functional. Similar correlation is observed with a hybrid and Coulomb-attenuated functional, but the errors become progressively smaller due to their increased fraction of exact, non-local exchange at long-range. The results are fully consistent with the diagnostic test of J. Chem. Phys. 128 (2008) 044118. (C) 2009 Elsevier B.V. All rights reserved.
KW - TRANSFER EXCITED-STATES
KW - Density functional theory
KW - TDDFT
KW - Rydberg states
KW - LOCAL-DENSITY
KW - EXCHANGE
KW - APPROXIMATION
KW - MODEL
KW - ORGANIC-COMPOUNDS
KW - AB-INITIO
KW - EXCITATION-ENERGIES
KW - ABSORPTION
KW - ASYMPTOTICALLY CORRECTED POTENTIALS
U2 - 10.1016/j.theochem.2009.03.009
DO - 10.1016/j.theochem.2009.03.009
M3 - Journal article
VL - 914
SP - 110
EP - 114
JO - Journal of Molecular Structure: THEOCHEM
JF - Journal of Molecular Structure: THEOCHEM
SN - 0166-1280
IS - 1-3
ER -