Band gap calculations
13587-13592Synthesises band-structure, DoS, PBE/HSE/GW/DFT+U caveats, and representative conductive-MOF band-gap comparisons.
Relevance: Core · 13587 · Band gap calculations
Federica Zanca, Lawson T. Glasby, Sanggyu Chong, Siyu Chen, Jihan Kim, David Fairen-Jimenez, Bartomeu Monserrat and Peyman Z. Moghadam · Journal of Materials Chemistry C · 2021
Summarise quantum-mechanical and machine-learning approaches for characterising and discovering electrically conductive MOFs, especially through band-structure, density-of-states and band-gap analysis.
The review’s argument is preserved as a navigable set of section summaries.
Synthesises band-structure, DoS, PBE/HSE/GW/DFT+U caveats, and representative conductive-MOF band-gap comparisons.
Relevance: Core · 13587 · Band gap calculations
Uses Fig. 1 to organise experimental methods, computational methods, DFT, ML and database-enabled discovery workflows.
Relevance: Core · 13585 · Introduction · Fig. 1
Concludes that periodic DFT remains central, method choice is context dependent, and ML is promising for triaging candidates but needs better data and uncertainty treatment.
Relevance: Core · 13595 · Conclusions
Explains when low-level DFT, dispersion corrections, fixed cell parameters or hybrid functionals are used for MOF geometry preparation.
Relevance: Supporting · 13587 · Geometry optimisation
Frames conductive MOFs as uncommon but valuable porous electronic materials and introduces through-bond and through-space charge-transport routes.
Relevance: Core · 13584 · Introduction
Reviews ML charge assignment, metallicity screening, QMOF/CGCNN/SOAP band-gap prediction and low-band-gap candidate discovery.
Relevance: Core · 13592 · Machine learning for characterisation of conductive MOFs
Reviews WFT, DFT and GW, then focuses on practical DFT choices including functionals, basis sets, pseudopotentials and k-point sampling.
Relevance: Core · 13586 · Quantum mechanical methods for characterisation of conductive MOFs
Classification systems are attributed to this review and are not treated as a global material registry.
The review uses broad band-gap ranges to interpret whether conductive behaviour is expected from a material.
Categories: zero band gap conductors · 0-3 eV semiconductors · above about 4 eV insulators
13585 · Introduction
Conductive MOFs are organised by whether charge transport is installed through extended bonding networks or by spatial orbital overlap.
Categories: through-bond extended pi-pi or pi-d conjugation · through-space overlapping orbitals
13584 · Introduction
Fig. 1 maps characterisation from experimental/computational methods through electronic-structure study and screening outputs.
Categories: experimental methods · computational methods · comparison with experiment · discovery of new MOFs · use of existing databases
13585 · Introduction · Fig. 1
ML methods are grouped by whether they estimate charges, classify metallicity, regress band gaps, or reduce candidates for detailed calculations.
Categories: partial-charge prediction · metallic/non-metallic classification · band-gap regression · candidate triage for high-level DFT
13593 · Machine learning for characterisation of conductive MOFs · Fig. 8
The review distinguishes full periodic MOF calculations from molecular fragments used to probe conformations and HOMO-LUMO effects.
Categories: periodic crystal structure · non-periodic molecular building block
13585 · Introduction
Review-defined families retain their representative materials and conduction descriptions.
HKUST-1 and redox-active guest variants such as TCNQ@HKUST-1.
Conduction: TCNQ insertion creates donor-acceptor coupling and new states in the MOF HOMO-LUMO gap.
Representative materials: HKUST-1 · TCNQ@HKUST-1
Nodes / linkers: Cu paddlewheel · BTC · TCNQ guest
13592 · Band gap calculations
Isostructural trivalent-metal MIL-53 frameworks with large-pore and narrow-pore conformations.
Conduction: Band gaps change with pore conformation because narrower pores increase linker overlap.
Representative materials: Ti-MIL-53 · Fe-MIL-53 · V-MIL-53 · Sc-MIL-53 · Cr-MIL-53 · In-MIL-53 · Ga-MIL-53 · Al-MIL-53
Nodes / linkers: Ti · Fe · V · Sc · Cr · In · Ga · Al · MIL-53 dicarboxylate framework
13591 · Band gap calculations · Fig. 6
Framework materials from CSD/QMOF screening predicted to have low DFT+PBE band gaps and selected for follow-up.
Conduction: Low predicted band gap is treated as a triage signal, not proof of high conductivity.
Representative materials: RAXNEK · OTARUX · WAQMEJ · FAFJAZ · HIVPOU
Nodes / linkers: Fe · Ag · Rh · Cu · Ni/Cu · TCNQ derivatives · polyoxovanadate units · fluorinated or metal-fluoride species · pdt-type ligands
13595 · Notable low band gap materials found via machine learning · Table 2
MOF-74-type frameworks including Fe/Co/Mg variants and NDI/TTF-modified DSNDI-MOF-74 analogues.
Conduction: Band-gap tuning is discussed through DFT+U, redox-active ligands and donor-acceptor guest interactions.
Representative materials: Fe-MOF-74 · Co-MOF-74 · Mg-MOF-74 · DSNDI-MOF-74 · TTF-DSNDI-MOF-74
Nodes / linkers: Fe · Co · Mg · DOBDC-type · naphthalenediimide · tetrathiafulvalene guest/dopant
13592 · Band gap calculations
Layered conductive MOFs based on HITP, HHTP, HHTT or related linkers with transition-metal or lanthanide nodes.
Conduction: High conductivity is linked to in-plane pi/d conjugation and/or interlayer pi-pi stacking.
Representative materials: Ni-HITP · Cu-HITP · M-HHTT · La-HHTP · Cu-BHT
Nodes / linkers: Ni · Cu · Co · Mg · lanthanides · hexaiminotriphenylene · hexahydroxytriphenylene · hexahydroxy tetraazanaphthotetraphene · benzenehexathiol
13591 · Band gap calculations · Fig. 5
Zr- or Ce-based UiO frameworks with BDC/BPDC/TPDC linkers and functionalised analogues.
Conduction: Band gaps are sensitive to linker length, hydroxylation state, metal substitution and functional groups.
Representative materials: UiO-66 · UiO-67 · UiO-68 · UiO-66(Ce)
Nodes / linkers: Zr6O4(OH)4 · Ce · BDC · BPDC · TPDC · functionalised BDC
13591 · Band gap calculations
Review-level synthesis principles remain separate from primary-study recipes.
Exploit pore breathing, interlayer distance or cell-volume changes to alter orbital overlap.
Claimed effects: Narrower pores or shorter stacking distances can reduce band gaps by increasing orbital overlap.
Controlling variables: pore conformation · pressure · temperature · gas adsorption · interlayer distance
Representative materials: M-MIL-53 · Ln-HHTP
Caveat: Applicability depends on flexible or layered structures and should be separated from irreversible chemical modification.
13591 · Band gap calculations
Introduce redox-active guests or dopants to create donor-acceptor interactions and new electronic states inside the MOF gap.
Claimed effects: Can create new charge-transport pathways and significantly increase conductivity.
Controlling variables: guest identity · host-guest electronic coupling · solvation state · doping level
Representative materials: TCNQ@HKUST-1 · TTF-DSNDI-MOF-74
Caveat: Guest or solvent state can make the resulting conductivity extrinsic and condition-sensitive.
13592 · Band gap calculations
Modify linker substituents to tune band gaps while preserving a common parent framework for comparison.
Claimed effects: Can narrow band gaps and make systematic structure-property comparisons possible.
Controlling variables: functional group identity · linker electronic character · parent framework consistency
Representative materials: UiO-66(Ce) · IRMOF-1 · IRMOF-20
Caveat: Presented as case-study evidence rather than a universal rule.
13592 · Band gap calculations · Fig. 7
Change metal nodes in related frameworks to alter d-orbital contributions, spin states and metal-ligand overlap.
Claimed effects: Can identify additional conductive analogues and change band gaps across a family.
Controlling variables: metal identity · open-shell character · metal-ligand orbital overlap
Representative materials: M-HITP · M-HHTT · M-MIL-53
Caveat: Open-shell transition metals can require hybrid or corrected methods for credible band gaps.
13591 · Band gap calculations
Use ML models to down-select large MOF/material spaces before expensive DFT or experimental validation.
Claimed effects: Greatly reduces screening cost and can recover previously known conductive or semiconductive candidates.
Controlling variables: training-set chemistry · descriptors or graph representation · band-gap threshold · validation by HSE/experiment
Representative materials: CSD-42362 · QMOF · RAXNEK · WAQMEJ · OTARUX
Caveat: Positive low-band-gap or metallic predictions do not guarantee conductivity.
13593 · Machine learning for characterisation of conductive MOFs · Fig. 8
These are the review authors’ synthesis, not newly measured results.
Band gap helps screen candidates, but band structure and DoS are also needed to understand electronic states and likely carrier behaviour.
Evidence basis: review_reasoning
Caveat: This does not replace direct conductivity or mobility measurements.
13587 · Band gap calculations
Conductive MOFs are uncommon because porosity, redox-inactive linkers and hard metal ions often impede charge delocalisation.
Evidence basis: review_reasoning
Caveat: Broad field-level tendency, not a quantitative prevalence estimate.
13584 · Introduction
DFT is the main practical method for periodic electronic-structure calculations in conductive MOFs because it balances cost and accuracy.
Evidence basis: review_reasoning
Caveat: GW and wave-function methods are discussed but are usually too expensive for broad MOF studies.
13586 · Quantum mechanical methods for characterisation of conductive MOFs
Geometry-optimisation method choice depends on material size, computational resources and the number of structures; low-level DFT may be justified for first-step screening.
Evidence basis: multi_reference
Caveat: High-level calculations remain appropriate for selected outstanding materials or flexible structures.
13587 · Geometry optimisation
Guest molecules or dopants can create donor-acceptor pathways and new gap states, changing apparent conductivity and band gaps.
Evidence basis: multi_reference
Caveat: Such behaviour may be extrinsic and sensitive to solvent or guest state.
13592 · Band gap calculations
For HHTT-based 2D MOFs, zero band gap alone is not enough; band dispersion and orbital contributions explain why Cu-HHTT is interpreted as more conductive than Co-HHTT.
Evidence basis: single_reference
Caveat: The review summarises one family as an interpretive example.
13588 · Band gap calculations · Fig. 2
HITP/HHTP/HHTT-type 2D MOFs are interpreted through in-plane metal-ligand conjugation and interlayer pi-pi stacking.
Evidence basis: multi_reference
Caveat: Individual materials still require primary transport and structural evidence.
13591 · Band gap calculations
LDA/GGA functionals such as PBE tend to underestimate band gaps, while HSE-type hybrid functionals often give values closer to experiment.
Evidence basis: multi_reference
Caveat: HSE is more expensive and can require fewer k-points or Gamma-only treatment in large MOFs.
13588 · Band gap calculations
Low predicted band gap is not sufficient for good electrical conductivity because defects, disorder and thermal effects can also control resistance.
Evidence basis: multi_reference
Caveat: Candidate lists should be treated as triage, not evidence of device-level transport.
13594 · Notable low band gap materials found via machine learning
M-MIL-53 pore conformation changes can tune band gaps because narrow pores increase neighbouring-linker orbital overlap.
Evidence basis: single_reference
Caveat: The review notes Ti-MIL-53 as an exception to the general lp versus np pattern.
13591 · Band gap calculations · Fig. 6
Binary metallic/non-metallic ML screens may miss semiconducting MOFs and a positive metallic prediction does not guarantee conductivity.
Evidence basis: single_reference
Caveat: Useful as a screening caveat for Chapter 1 ML discussion.
13593 · Machine learning for characterisation of conductive MOFs
ML can reduce very large MOF search spaces to manageable candidate sets for high-level DFT and experimental follow-up.
Evidence basis: multi_reference
Caveat: Requires relevant, diverse training data and later validation.
13592 · Machine learning for characterisation of conductive MOFs
MOFs containing open-shell transition metals are difficult for most DFT functionals because of spin-state and electronic-structure complications.
Evidence basis: multi_reference
Caveat: The review suggests hybrid DFT for more realistic band-gap descriptions in such cases.
13589 · Band gap calculations
The review identifies a lack of systematic structure-conductivity investigation across MOF chemistries, limiting rational correlations.
Evidence basis: review_reasoning
Caveat: This is the review authors outlook rather than a meta-analytic result.
13595 · Conclusions
The review interprets conductive MOF design mainly through through-bond conjugation and through-space orbital-overlap pathways.
Evidence basis: review_reasoning
Caveat: A simplifying taxonomy across heterogeneous materials.
13584 · Introduction
Every row remains visibly secondary and links to a primary dossier only where the mapping is verified.
| Material | Property | Reported value | Context and quality | Primary evidence | Review source |
|---|---|---|---|---|---|
| SecondaryQMOF/CSD-42362 MOF subset | ML versus DFT compute time | 7 minutes for 13,058 MOFs versus 1.5 million hours via DFT+PBE | Review summary of CGCNN screening versus DFT+PBE computation Text · Exact Reported | No verified corpus mapping | 13594 · Machine learning for characterisation of conductive MOFs |
| SecondaryQMOF/CSD-42362 MOF subset | CGCNN band-gap prediction performance | MAE 0.27 eV; R2 0.89 | ML prediction of DFT-computed band gaps for optimised MOF structures Text · Exact Reported | No verified corpus mapping | 13593 · Machine learning for characterisation of conductive MOFs · Fig. 9 |
| SecondaryCu(TCNQCl2) / FAFJAZ | ML-screened band gap | DFT+PBE predicted 0.009 eV; experimental 0.032 eV | Table 2 notable conductive materials identified using ML techniques Table · Exact Reported | No verified corpus mapping | 13595 · Notable low band gap materials found via machine learning · Table 2 |
| SecondaryDSNDI-MOF-74 | band gap | PBE 1.6 eV; HSE06 2.5 eV; experimental 2.1 eV | Table 1 and text summary before TTF guest doping Text · Exact Reported | research_0182 | 13592 · Band gap calculations |
| SecondaryFe-MOF-74 | band gap comparison | PBE/DFT+U 0.3-1.75 eV; HSE06 1.38-2.44 eV; experimental 2.1-1.3 eV | Table 1 secondary summary; includes Hubbard-corrected values in footnote Table · Range | No verified corpus mapping | 13590 · Band gap calculations · Table 1 |
| SecondaryLa-HHTP | directional band gap | 1.5 eV in-plane; no band gap out-of-plane | Review text interpreting band structure and DoS Text · Range | research_0047 | 13591 · Band gap calculations · Fig. 5 |
| SecondaryM-HHTT | band gap | 0 eV PBE | Table 1 secondary summary and Fig. 2 discussion for layered HHTT MOFs Table · Exact Reported | No verified corpus mapping | 13590 · Band gap calculations · Table 1 |
| SecondaryM-MIL-53 | lp-np band-gap difference | 0.35 eV for V3+ to 1.39 eV for In3+ | HSE06 comparison of large-pore and narrow-pore conformations Text · Range | No verified corpus mapping | 13591 · Band gap calculations · Fig. 6 |
| SecondaryNi-HITP | band gap | PBE 0.12 eV; HSE06 0.2/0 eV | Table 1 secondary summary; low-level and high-level DFT values Table · Range | No verified corpus mapping | 13590 · Band gap calculations · Table 1 |
| SecondaryFe(squarate)(bpee)(H2O)2 / RAXNEK | ML-screened band gap | DFT+PBE predicted 0.382 eV; reported 1.06 eV by HSE06-D3(BJ) | Table 2 notable conductive materials identified using ML techniques Table · Exact Reported | No verified corpus mapping | 13595 · Notable low band gap materials found via machine learning · Table 2 |
| SecondaryTCNQ@HKUST-1 | electrical conductivity increase | six orders of magnitude to 7 x 10^-2 S cm^-1 | TCNQ infiltration of HKUST-1; secondary review summary of original work Text · Approximate | research_0088 | 13592 · Band gap calculations |
| SecondaryTTF-DSNDI-MOF-74 | band gap | PBE 0.9 eV; HSE06 1.5 eV; experimental 1 eV | Table 1 and review text after TTF guest doping Text · Exact Reported | research_0182 | 13592 · Band gap calculations |
| SecondaryUiO-66(Ce) | functionalisation band-gap narrowing | from 2.66 eV to 1 eV with SH and NH functional groups | HSE06 calculated DoS of functionalised UiO-66(Ce) Text · Approximate | No verified corpus mapping | 13592 · Band gap calculations · Fig. 7 |
| SecondaryUiO-66 | band gap comparison | PBE 2.92 eV; HSE06 4.03 eV; experimental ca. 3.94-4.07 eV | Review text/Table 1 comparison of low-level, high-level and experimental band gaps Text · Range | No verified corpus mapping | 13591 · Band gap calculations · Table 1 |
| Secondary(TTF)[Rh2(CH3CO2)4]2TCNQ / WAQMEJ | ML-screened band gap | DFT+PBE predicted 0.151 eV; reported 0.71 eV by HSE06-D3(BJ) | Table 2 and Fig. 10 low-band-gap candidate context Table · Exact Reported | No verified corpus mapping | 13595 · Notable low band gap materials found via machine learning · Table 2 |
Open questions are presented as review-author priorities, not conclusions from the primary database.
The review states that the nature of conductivity in MOFs is not yet explicitly understood at the atomistic level.
Proposed direction: Develop atomistic models that identify low-energy charge-transport pathways and compare them against transport measurements.
13584 · Abstract
Measured band gaps can vary with technique, synthesis, environment and post-treatment conditions.
Proposed direction: Pair computational benchmarks with careful experimental metadata and uncertainty reporting.
13589 · Band gap calculations
The review calls for better reference band-gap calculations and methods to quantify prediction uncertainty.
Proposed direction: Report uncertainty estimates alongside ML candidate rankings and validate promising cases with high-level DFT/experiment.
13596 · Conclusions
ML studies may struggle with rare elements and hypothetical chemistry that are absent from training data.
Proposed direction: Expand training sets to chemically diverse MOFs and include more exact MOF-specific reference calculations.
13593 · Machine learning for characterisation of conductive MOFs
Electronic structures of MOFs containing open-shell metals are difficult for most DFT functionals.
Proposed direction: Use hybrid or otherwise corrected methods and benchmark against experiments for Ti, V, Fe and related systems.
13589 · Band gap calculations
The review identifies a lack of systematic investigation over wide MOF chemistries, limiting rational structure-conductivity correlations.
Proposed direction: Build comparative datasets that vary metal nodes, linkers, guests and defects while controlling computational and experimental protocols.
13595 · Conclusions
Mappings show which printed review references have a verified counterpart in the frozen primary corpus.
| Reference | Study | Role and context | Corpus mapping |
|---|---|---|---|
| Ref. 1042019 | Title unavailable | solvation_caveat · ml_candidateSelected for the review caveat that conductivity can be sensitive to solvated state. | research_0052 |
| Ref. 782014 | Title unavailable | open_shell_caveat · band_gap_benchmarkCited for transition-metal/open-shell and DFT band-gap limitations in MOFs. | Unmapped |
| Ref. 922015 | Title unavailable | band_gap_benchmark · hitp_familyOriginal Ni-HITP/Cu-HITP band-gap benchmark used in Table 1 and review discussion. | Unmapped |
| Ref. 1362019 | Title unavailable | database_contextDatabase context for ML screening and the scale of available computational MOF structures. | Unmapped |
| Ref. 1532014 | Title unavailable | ml_candidate · band_gap_benchmarkSource for Table 2 reported band gaps of selected Fe-containing ML-screened candidates. | Unmapped |
| Ref. 762013 | Title unavailable | open_shell_caveatCited in the review for difficulty of describing transition metals with unpaired electrons. | Unmapped |
| Ref. 512021 | Title unavailable | band_structure · transport_benchmarkOriginal HHTT study used by the review for band-structure/DoS comparison and zero-band-gap family benchmark. | Unmapped |
| Ref. 912016 | Title unavailable | metal_substitution · hitp_familyCited for further M-HITP metal substitution after Ni-HITP calculations. | Unmapped |
| Ref. 1002017 | Title unavailable | guest_doping · band_gap_benchmarkProvides DSNDI-MOF-74 and TTF-doped DSNDI-MOF-74 band-gap benchmarks and donor-acceptor interpretation. | research_0182 |
| Ref. 1412018 | Title unavailable | ml_screening · metallicity_classificationFirst ML application described by the review for conductive MOF metallicity prediction using descriptors and multi-voting. | research_0682 |
| Ref. 772013 | Title unavailable | open_shell_caveat · transition_metalsCited in the review discussion of electronic-structure and open-shell/transition-metal DFT limitations. | Unmapped |
| Ref. 882015 | Title unavailable | guest_doping · transport_mechanismUsed for computational mechanism of TCNQ-induced conductance in HKUST-1. | Unmapped |
| Ref. 532015 | Title unavailable | band_gap_benchmark · uio_familySelected because Table 1 and text use UiO-66 HSE/PBE/experiment comparison as a key band-gap benchmark. | Unmapped |
| Ref. 141964 | Title unavailable | method_foundationFoundational density-based DFT reference used in the review explanation of electronic structure calculations. | Unmapped |
| Ref. 462006 | Title unavailable | method_foundation · hybrid_functionalHybrid-functional reference cited for high-level band-gap and geometry calculations. | Unmapped |
| Ref. 131965 | Title unavailable | method_foundationFoundational DFT reference cited in the review quantum-mechanical methods discussion. | Unmapped |
| Ref. 82020 | Title unavailable | transport_pathway_reviewCited by the review for through-bond and through-space charge-transport pathway framing. | Unmapped |
| Ref. 402015 | Title unavailable | band_gap_benchmark · flexible_frameworksOriginal M-MIL-53 conformation/band-gap benchmark used for flexibility-driven electronic tuning. | Unmapped |
| Ref. 1542010 | Title unavailable | ml_candidate · band_gap_benchmarkSource for Table 2 Cu(TCNQCl2) experimental low-band-gap benchmark. | Unmapped |
| Ref. 602014 | Title unavailable | linker_functionalisation · homo_lumoUsed for halogen/linker modification HOMO-LUMO and band-gap trends. | Unmapped |
| Ref. 1052021 | Title unavailable | ml_screening · qmof · band_gap_predictionMain review source for QMOF, CGCNN/SOAP performance, ML-screened candidates and Table 2 context. | Unmapped |
| Ref. 1502017 | Title unavailable | ml_candidate · band_gap_benchmarkSource for the WAQMEJ low-band-gap candidate reported in Table 2 and Fig. 10 context. | Unmapped |
| Ref. 452014 | Title unavailable | geometry_optimisation · vdw_correctionCited as an example where PBE-D2 accounted for strong van der Waals interactions in layered Ni-HITP. | Unmapped |
| Ref. 932020 | Title unavailable | band_structure · dimensionalityUsed for lanthanide-HHTP anisotropic band-gap and stacking-distance interpretation. | research_0047 |
| Ref. 1292014 | Title unavailable | guest_doping · transport_benchmarkOriginal TCNQ infiltration work summarised for conductivity increase and charge-transfer mechanism. | research_0088 |
| Ref. 1282018 | Title unavailable | linker_functionalisation · band_gap_benchmarkOriginal functionalised UiO-66(Ce) study used for band-gap narrowing benchmark. | Unmapped |
| Ref. 62020 | Title unavailable | conductive_mof_context · transport_caveatCited by the review for broader conductive-MOF context and caveats around defects and transport. | Unmapped |
| Ref. 542013 | Title unavailable | band_gap_benchmark · dft_uOriginal MOF-74 DFT+U band-gap example used to discuss system-specific correction schemes. | Unmapped |