Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Transition-Based Constrained DFT for the Robust and Reliable Treatment
  of Excitations in Supramolecular Systems   Despite the variety of available computational approaches, state-of-the-art
methods for calculating excitation energies such as time-dependent density
functional theory (TDDFT), are computationally demanding and thus limited to
moderate system sizes. Here, we introduce a new variation of constrained DFT
(CDFT), wherein the constraint corresponds to a particular transition (T), or
combination of transitions, between occupied and virtual orbitals, rather than
a region of the simulation space as in traditional CDFT. We compare T-CDFT with
TDDFT and $\Delta$SCF results for the low lying excited states (S$_{1}$ and
T$_{1}$) of a set of gas phase acene molecules and OLED emitters, as well as
with reference results from the literature. At the PBE level of theory, T-CDFT
outperforms $\Delta$SCF for both classes of molecules, while also proving to be
more robust. For the local excitations seen in the acenes, T-CDFT and TDDFT
perform equally well. For the charge-transfer (CT)-like excitations seen in the
OLED molecules, T-CDFT also performs well, in contrast to the severe energy
underestimation seen with TDDFT. In other words, T-CDFT is equally applicable
to both local excitations and CT states, providing more reliable excitation
energies at a much lower computational cost than TDDFT. T-CDFT is designed for
large systems and has been implemented in the linear scaling BigDFT code. It is
therefore ideally suited for exploring the effects of explicit environments on
excitation energies, paving the way for future simulations of excited states in
complex realistic morphologies, such as those which occur in OLED materials.

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The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
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The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
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The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
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The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-lat