Description
Return spherical rotational diffusivity and second-rank correlation time.
Diffusive and thermal scales depend on dimensionality, geometry, drag and compatible energy/time units. A local displacement correction or ideal spherical diffusivity is distinct from fitting a stochastic trajectory or establishing that a measured system satisfies the model.
Return spherical rotational diffusivity and second-rank correlation time.
When to use this tool
Use Rotational Diffusion Viscosity Radius Term when checking the stated diffusion, drift, work or thermal-energy convention.
How to use the tool and how it works
- Enter thermalEnergy, viscosity, radius. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read rotationalDiffusivity, secondRankCorrelationTime. Use the output convention below.
Return spherical rotational diffusivity and second-rank correlation time. Require positive thermalEnergy, viscosity and radius; D = thermalEnergy/(8*pi*viscosity*radius³), correlation time = 1/(6*D).1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| thermalEnergy | kB*T, not temperature alone; SI joules with viscosity Pa s and radius m give D in s^-1. | Required. Finite number; strictly above 0. |
| viscosity | Viscosity | Required. Finite number; strictly above 0. |
| radius | Radius | Required. Finite number; strictly above 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| rotationalDiffusivity | Rotational Diffusivity | Required. Finite number. |
| secondRankCorrelationTime | Second Rank Correlation Time | Required. Finite number. |
{
"input": {
"thermalEnergy": 25.132741228718345,
"viscosity": 1,
"radius": 1
},
"output": {
"rotationalDiffusivity": 1,
"secondRankCorrelationTime": 0.16666666666666666
}
}Limitations and assumptions
- This uses an ideal no-slip spherical hydrodynamic model; real shape, boundaries and viscosity dependence are not inferred.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use calibrated trajectories and an appropriate geometry/noise/transport model for fitted diffusion parameters, uncertainty or molecular mechanisms.
References
Similar or alternative tools
- Diffusion Stokes Einstein Radius Factor
Return spherical translational Stokes-Einstein diffusivity.
- Diffusion Time Scale Ratio
Return a ratio of diffusive time scales.