Harmonic vibrational partition and energy zero
For one harmonic normal mode, a geometric sum gives its vibrational partition function.
Key knowledge
For one harmonic normal mode, a geometric sum gives its vibrational partition function. Including zero-point energy or choosing the lowest vibrational level as zero produces different partition factors with consistent physical energy accounting. Mode excitation can be suppressed at temperatures low relative to its characteristic vibrational temperature.
Values and equations
θv = hν/kB; qvib = exp(−θv/(2T))/(1−exp(−θv/T)); qvib* = 1/(1−exp(−θv/T))
- θv
- characteristic vibrational temperature K
- h
- Planck constant J s
- ν
- mode frequency Hz
- kB
- Boltzmann constant J K⁻¹
- T
- absolute temperature K
- qvib
- partition contribution with potential minimum as energy zero 1
- qvib*
- partition contribution with v=0 level as energy zero 1
Conditions and scope
- Independent harmonic modes approximate small-amplitude motion about a stable structure.
- Anharmonicity, coupling and dissociation limit high-excitation extrapolation; no universal temperature cutoff is asserted.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read harmonic geometric sum and alternative ground-state energy reference; excluded the table's partition-below-one error and unqualified all-temperature applicability.
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Entry details
Permanent link to this entry ↗- Record identity
- uni-chem-vibrational-partition
- Revision
- core.1
- Structured reference record
- University core expansion