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Small Angle Scattering



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© ATSAS Team, 2017

Table of Contents


The following sections shortly describe the method implemented in DATABSMW, how to run DATABSMW from the command-line on any of the supported platforms and the required input files.


If the data collected has been scaled to an absolute scale (see DATABSOLUTE), then the molecular weight can be determined knowing the forward scattering, concentration, contrast and partial specific volume of the sample (Jeffries et. al 2016, p.2144 eq. 5). Determining the MW from absolute scale means that no protein standard is used, and therefore it is not assumed that the partial specific volume and contrast of the sample is the same to that of the protein standard. Therefore, for most accurate results the partial specific volume and contrast should be determined for each sample (Jeffries et. al 2016, p. 2130). If these two values are not known, empirically averaged values may be used (Mylonas & Svergun, 2008).

Running databsmw


$ databsmw <FILE> <i0> [OPTIONS] 

OPTIONS known by DATABSMW are described in next section, the 'FILE' argument in the section on input files.

Command-line arguments and options

Absolute as well as relative paths to data files are accepted. Up to one of the input files may also be given as '-', in this case input is read from stdin instead of a file.

DATABSMW recognizes following command-line options:

Short optionLong optionDescription
--psv Override the standard partial specific volume from Mylonas & Svergun, 2008.
--contrast Override the standard contrast from Mylonas & Svergun, 2008. The contrast input should be in units of 10^10.
--i0 The i0 of the sample on an absolute scale.
-v --version Print version information and exit.
-h --help Print a summary of arguments and options and exit.

Runtime output

The molecular weight from absolute scaling and the input file name are printed to stdout.

databsmw input files

Input files for databsmw may be in any of the supported data formats as long as scattering vector, experimental intensity and errors are available. The experimental intensities should be on an absolute scale, for instance those produced by DATABSOLUTE.


$ databsmw bsa_absolute_003.dat --i0 0.005677 --psv 0.732 --contrast 2.56
  72   bsa_absolute_003.dat

  Last modified: June 26, 2017

© BioSAXS group 2017