NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
This chapter presents a high-level description of a suite of programs denoted by the acronym OCEAN (Obtaining Core Excitation spectra ab initio and with NBSE), where NBSE denotes the underlying NIST Bethe-Salpeter Equation program. The main computational steps, physical approximations made and overall scope of the required user input are discussed. Several examples of calculation results are presented for a variety of systems. We also discuss future improvements and extensions that are being considered at this time, and discuss how to access the program and its extensive documentation.
Citation
International Tables for Crystallography: Volume I, X-ray Absorption Spectroscopy and Related Techniques
, E.
, Vinson, J.
and Gilmore, K.
(2021),
The OCEAN Project, International Tables for Crystallography: Volume I, X-ray Absorption Spectroscopy and Related Techniques, International Union of Crystallography, Chester, , [online], https://doi.org/10.1107/S157487072000333X, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=921289
(Accessed October 9, 2025)