Define antibonding molecular orbitals .

Explanation

### Step-by-Step Solution:

1. **Understanding Molecular Orbitals**:
- Molecular orbitals are formed when atomic orbitals combine. This combination can lead to two types of molecular orbitals: bonding and antibonding.

2. **Definition of Antibonding Molecular Orbitals**:
- Antibonding molecular orbitals are formed when atomic orbitals combine in such a way that they create a molecular orbital of higher energy than the original atomic orbitals.

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