TOPS Opacities

Opacities of mixtures (calculated by TOPS^® using LEDCOP^® elemental opacities)

The latest materials were added on March 31, 2000.

Users are encouraged to view the File of currently available materials page to learn about the new data options.

Link to: Los Alamos Astrophysical Opacity Page

Precalculated Rosseland opacity tables for complex astrophysical mixtures are now available.

Fill in form, then submit. Multiple values (where appropriate) must be separated by spaces. Leave field empty for default value. As a help to new users, the initial Web page defaults to calculating gray mean opacities for aluminum.

Relevant information:

• File of currently available materials
• Help
• Frequently asked questions
• Opacity methods and references
• Disclaimer
• Graphics and data options

LEDCOP (new) OPLIB77* Most recent available
*Contains known inaccuracies, but provided for historical comparisons.

Fraction by Number or Mass.
Input format is Fraction, Element or Fraction, Element, Isotopic weight.

In specifying a mix, the fraction represents relative numbers of atoms if the number fraction box is checked. If the mass fraction box is checked, the fraction represents relative masses of the specified elements. The fractions need not be normalized.

The element specification can be the atomic number, the chemical symbol (case insensitive) or the OPLIB matid. Thus aluminum can be specified as Al, al, 13, l13718 or n13718 (for the new denser photon energy grids).

If the "Fraction, Element, Isotope" box is checked, a specific isotopic weight must be entered for each element of the mixture. If this box is not checked, no isotopic weight should be entered, the Web Page will use the normal values.

User specified mixture. Up to 450 characters may be used for the mixture specification. User can choose to supply a name for the mixture, up to 15 characters.


Optional Mixture Name: (User supplied, maximum of 15 characters)

Specific temperatures--must be in data base, see range values below or Temperature list

Temperature range:Minimum: 0.0005 0.0006 0.0008 0.001 0.00125 0.0015 0.002 0.0025 0.003 0.0035 0.004 0.005 0.006 0.008 0.01 0.0125 0.015 0.02 0.025 0.03 0.04 0.05 0.06 0.08 0.1 0.125 0.15 0.2 0.25 0.3 0.4 0.5 0.6 0.8 1 1.25 1.5 2 2.5 3 4 5 6 8 10 15 25 40 60 100Maximum: 0.0005 0.0006 0.0008 0.001 0.00125 0.0015 0.002 0.0025 0.003 0.0035 0.004 0.005 0.006 0.008 0.01 0.0125 0.015 0.02 0.025 0.03 0.04 0.05 0.06 0.08 0.1 0.125 0.15 0.2 0.25 0.3 0.4 0.5 0.6 0.8 1 1.25 1.5 2 2.5 3 4 5 6 8 10 15 25 40 60 100
Thin database table by factor of

Specific densities:

values (max  100) in range to with linear log spacing
Read Standard SESAME densities) to get normal SESAME library density grid.

Specific photon energies (at least 2 if this option is chosen):

values (max 1000) in range to with linear log spacing
Photon energy grid need not be specified for gray mean opacities or frequency dependent opacities.