The most stable structures of tetrahedral M42+ cluster (M = Cu, Ag, Au)encapsulated in SAPO-42 zeolite -cage have been determined by the DFT methodusing a/the B3LYP functional and LANL2DZ basis set. Electronic energies, zeropoint correction to energies and geometries, as well as the charge of the clusters,have been derived accordingly. The results showed that while the Cu-Cu bond lengthincreases much when Cu42+ is in the framework, the Ag-Ag and Au-Au distances donot. The UV-Vis spectra of the [M4@SAPO-42]2+ clusters, which were calculatedat the same hybrid B3LYP functional and the LANL2DZ basis set, show strongabsorption peaks at 259 nm, 270 nm, and 259 nm for M being Cu, Ag, and Au,respectively. The nature of electronic transitions that are responsible for theabsorption peaks in the UV-Vis spectrum of the [M4-SAPO-42]2+ clusters hasbeen revealed.The most stable structures of tetrahedral M42+ cluster (M = Cu, Ag, Au)encapsulated in SAPO-42 zeolite -cage have been determined by the DFT methodusing a/the B3LYP functional and LANL2DZ basis set. Electronic energies, zeropoint correction to energies and geometries, as well as the charge of the clusters,have been derived accordingly. The results showed that while the Cu-Cu bond lengthincreases much when Cu42+ is in the framework, the Ag-Ag and Au-Au distances donot. The UV-Vis spectra of the [M4@SAPO-42]2+ clusters, which were calculatedat the same hybrid B3LYP functional and the LANL2DZ basis set, show strongabsorption peaks at 259 nm, 270 nm, and 259 nm for M being Cu, Ag, and Au,respectively. The nature of electronic transitions that are responsible for theabsorption peaks in the UV-Vis spectrum of the [M4-SAPO-42]2+ clusters hasbeen revealed.