LUMO guides
Clear, referenced explanations of frontier molecular orbitals, energy units and the computational methods behind every result on this site. Start with the basics or jump to the topic you need.
What Is LUMO in Chemistry?
A first look at the lowest unoccupied molecular orbital: where it sits in the orbital energy ladder, how it differs from the HOMO, and why it predicts where a molecule accepts electrons.
Read the guideHOMO vs. LUMO
How the highest occupied and lowest unoccupied orbitals differ, and how each relates to donating or accepting electrons.
Read guide FormulasHOMO-LUMO Gap Formula
The gap as E(LUMO) minus E(HOMO), worked examples with unit conversion, and why the orbital gap is not the optical gap.
Read guide InterpretationLUMO Energy Meaning
What high and low LUMO energies suggest about electron affinity, electrophilicity and ease of reduction.
Read guide UnitsLUMO Energy in eV
Converting between Hartree, electronvolts and kJ/mol, with exact factors and the sign conventions that cause most mistakes.
Read guide MethodsHow LUMO Energy Is Calculated
From structure to orbital energies: geometry, basis sets and methods, and what each choice changes in the result.
Read guide ReferenceMethodology
The engine, methods, unit definitions and assumptions behind this calculator, documented in one place.
View methodologyPut the theory into practice
Run a molecule LUMO calculation on any small molecule and compare the result with what you have read.