Source: https://guthlabs.ai/docs/instruments/unit-cell-density-calculator/implementation/

instrument implementation / implementation-contract

# Unit Cell Density Calculator implementation

A source-bound implementation contract for Unit Cell Density Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t5-047

**Effect**: Computation or source lookup only

## Input and validation requirements

An extreme but representable lattice parameter of 1.0×10^-300 m causes JavaScript exponentiation to underflow a^3 to zero, producing Infinity instead of a finite density. The unit convention is also hazardous because interpreting a=0.36 as Å rather than nm changes the result by a factor of 1000.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "crystal_structure": "SC",
    "lattice_parameter": 0.3,
    "lattice_parameter_unit": "nm",
    "molar_mass": 40,
    "molar_mass_unit": "g/mol",
    "Z": 1
  },
  "expected_outputs": {
    "theoretical_density": 2.460115,
    "density_unit": "g/cm^3",
    "packing_factor": 0.523599
  },
  "working": "a=0.300 nm=3.00×10^-8 cm. Vcell=a^3=(3.00×10^-8)^3=2.700×10^-23 cm^3. Z·M=1×40.00=40.00 g/mol. Vcell·NA=(2.700×10^-23)(6.022×10^23)=2.700×6.022=16.2594. ρ=40.00/16.2594=2.460115 g/cm^3. PF=π/6=0.523599."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/unit-cell-density-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/unit-cell-density-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/unit-cell-density-calculator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`