REFERENCES
1. Imada, M.; Fujimori, A.; Tokura, Y. Metal-insulator transitions. Rev. Mod. Phys. 1998, 70, 1039-263.
3. Mizokawa, T.; Tjeng, L. H.; Sawatzky, G. A.; et al. Spin-orbit coupling in the Mott insulator Ca2RuO4. Phys. Rev. Lett. 2001, 87, 077202.
4. Takenaka, K.; Inoue, N.; Mizuno, Y.; et al. Extended operating temperature window of giant negative thermal expansion in Sn-doped Ca2RuO4. Appl. Phys. Lett. 2018, 113, 071902.
5. Alonso, J. A.; García-Muñoz, J. L.; Fernández-Díaz, M. T.; Aranda, M. A. G.; Martínez-Lope, M. J.; Casais, M. T. Charge disproportionation in RNiO3 perovskites: simultaneous metal-insulator and structural transition in YNiO3. Phys. Rev. Lett. 1999, 82, 3871-4.
6. Azuma, M.; Chen, W. T.; Seki, H.; et al. Colossal negative thermal expansion in BiNiO3 induced by intermetallic charge transfer. Nat. Commun. 2011, 2, 347.
7. Pachoud, E.; Cumby, J.; Lithgow, C. T.; Attfield, J. P. Charge order and negative thermal expansion in V2OPO4. J. Am. Chem. Soc. 2018, 140, 636-41.
8. Murota, K.; Pachoud, E.; Attfield, J. P.; et al. Charge correlation in V2OPO4 probed by hard x-ray photoemission spectroscopy. Phys. Rev. B. 2020, 101, 235159.
9. Murota, K.; Pachoud, E.; Attfield, J. P.; et al. Vanadium 3d charge and orbital states in V2OPO4 probed by x-ray absorption spectroscopy. Phys. Rev. B. 2020, 101, 245106.
10. Mizokawa, T.; Fujimori, A. Unrestricted hartree-fock study of transition-metal oxides: spin and orbital ordering in perovskite-type lattice. Phys. Rev. B. Condens. Matter. 1995, 51, 12880-3.
11. Mizokawa, T.; Fujimori, A. Electronic structure and orbital ordering in perovskite-type 3d transition-metal oxides studied by Hartree-Fock band-structure calculations. Phys. Rev. B. Condens. Matter. 1996, 54, 5368-80.
12. Kurokawa, M.; Mizokawa, T. Orbital state and metal-insulator transition in Ca2-xSrxRuO4 studied by model Hartree-Fock calculations. Phys. Rev. B. 2002, 66, 024434.
13. Naka, M.; Seo, H.; Motome, Y. Theory of valence transition in BiNiO3. Phys. Rev. Lett. 2016, 116, 056402.
14. Mizokawa, T.; Khomskii, D. I.; Sawatzky, G. A. Spin and charge ordering in self-doped Mott insulators. Phys. Rev. B. 2000, 61, 11263-6.
15. Yoshino, T.; Okawa, M.; Kajita, T.; et al. Unusual valence state and metal-insulator transition in BaV10O15 probed by hard x-ray photoemission spectroscopy. Phys. Rev. B. 2017, 95, 075151.
16. Mizokawa, T.; Tjeng, L. H.; Lin, H.; et al. Orbital state and metal-insulator transition in Ca2-xSrxRuO4 (x=0.0 and 0.09) studied by x-ray absorption spectroscopy. Phys. Rev. B. 2004, 69, 132410.
17. Nakamura, F.; Goko, T.; Ito, M.; et al. From mott insulator to ferromagnetic metal: a pressure study of Ca2RuO4. Phys. Rev. B. 2002, 65, 220402.
18. Steffens, P.; Friedt, O.; Alireza, P.; et al. High-pressure diffraction studies on Ca2RuO4. Phys. Rev. B. 2005, 72, 094104.
19. Keen, H. D. J.; Julian, S. R.; Hermann, A. Ab initio study of pressure-induced structural and electronic phase transitions in Ca2RuO4. Phys. Rev. B. 2021, 104, 085143.
20. Torrance, J. B.; Lacorre, P.; Nazzal, A. I.; Ansaldo, E. J.; Niedermayer, C. Systematic study of insulator-metal transitions in perovskites RNiO3 (R=Pr,Nd,Sm,Eu) due to closing of charge-transfer gap. Phys. Rev. B. Condens. Matter. 1992, 45, 8209-12.
21. Zhou, J. S.; Goodenough, J. B.; Dabrowski, B. Pressure-induced non-Fermi-liquid behavior of PrNiO3. Phys. Rev. Lett. 2005, 94, 226602.
22. Cheng, J.; Zhou, J.; Goodenough, J. B.; Alonso, J. A.; Martinez-lope, M. J. Pressure dependence of metal-insulator transition in perovskites RNiO3 (R=Eu , Y, Lu). Phys. Rev. B. 2010, 82, 085107.
23. Mizokawa, T.; Fujimori, A.; Arima, T.; Tokura, Y.; Mori, N.; Akimitsu, J. Electronic structure of PrNiO3 studied by photoemission and x-ray-absorption spectroscopy: band gap and orbital ordering. Phys. Rev. B. Condens. Matter. 1995, 52, 13865-73.
24. Johnston, S.; Mukherjee, A.; Elfimov, I.; Berciu, M.; Sawatzky, G. A. Charge disproportionation without charge transfer in the rare-earth-element nickelates as a possible mechanism for the metal-insulator transition. Phys. Rev. Lett. 2014, 112, 106404.
25. Green, R. J.; Haverkort, M. W.; Sawatzky, G. A. Bond disproportionation and dynamical charge fluctuations in the perovskite rare-earth nickelates. Phys. Rev. B. 2016, 94.
26. Wang, L.; Yang, Z.; Bowden, M. E.; et al. Hole-trapping-induced stabilization of Ni4 + in SrNiO3/LaFeO3 superlattices. Adv. Mater. 2020, 32, e2005003.
27. Paul, A.; Mukherjee, A.; Dasgupta, I.; Paramekanti, A.; Saha-Dasgupta, T. Hybridization-switching induced mott transition in ABO3 perovskites. Phys. Rev. Lett. 2019, 122, 016404.
28. Nishikubo, T.; Sakai, Y.; Oka, K.; et al. Optimized negative thermal expansion induced by gradual intermetallic charge transfer in
29. Pachoud, E.; Cumby, J.; Wright, J.; Raguz, B.; Glaum, R.; Attfield, J. P. Electronic origin of negative thermal expansion in V2OPO4. Chem. Commun. 2020, 56, 6523-6.
30. Chang, C.; Koethe, T.; Hu, Z.; et al. c-axis dimer and its electronic breakup: the insulator-to-metal transition in Ti2O3. Phys. Rev. X. 2018, 8, 021004.
31. Miyoshino, T.; Takegami, D.; Meléndez-Sans, A.; et al. Intra c-axis dimer hybridization and mixed valency in Mg-doped Ti2O3. Phys. Rev. B. 2023, 107, 115145.