<html>
  <head>
    <meta content="text/html; charset=utf-8" http-equiv="Content-Type">
  </head>
  <body bgcolor="#FFFFFF" text="#000000">
    Hi Charles,<br>
    <br>
    I think the key here is what you call "<span class="">no difference
      density peak</span>". Sites may be partially occupied so rule of
    thumb for choosing contouring levels for 2mFo-DFc and mFo-DFc maps
    (1 and 3 sigma, correspondingly) may not be appropriate, for
    instance.<br>
    <br>
    Pavel<br>
    <br>
    <div class="moz-cite-prefix">On 9/10/14 6:10 AM, CPMAS Chen wrote:<br>
    </div>
    <blockquote
cite="mid:CAAU4GKae_VtbWhtXaBrwtb1so_sxi4i_pf6zAcMiWHkxB8oMkg@mail.gmail.com"
      type="cite">
      <div dir="ltr">Thanks, Nat. 
        <div><br>
        </div>
        <div>If this is noise, why the anomalous or LLG peaks could be
          as high as 5 ~ 6 sigma? </div>
        <div><br>
        </div>
        <div>Charles</div>
      </div>
      <div class="gmail_extra"><br>
        <div class="gmail_quote">On Tue, Sep 9, 2014 at 5:58 PM,
          Nathaniel Echols <span dir="ltr">&lt;<a
              moz-do-not-send="true" href="mailto:nechols@lbl.gov"
              target="_blank">nechols@lbl.gov</a>&gt;</span> wrote:<br>
          <blockquote class="gmail_quote" style="margin:0 0 0
            .8ex;border-left:1px #ccc solid;padding-left:1ex">
            <div dir="ltr"><span class="">On Tue, Sep 9, 2014 at 8:40
                AM, CPMAS Chen <span dir="ltr">&lt;<a
                    moz-do-not-send="true"
                    href="mailto:cpmasmit@gmail.com" target="_blank">cpmasmit@gmail.com</a>&gt;</span>
                wrote:<br>
              </span>
              <div class="gmail_extra">
                <div class="gmail_quote"><span class="">
                    <blockquote class="gmail_quote" style="margin:0 0 0
                      .8ex;border-left:1px #ccc solid;padding-left:1ex">
                      <div dir="ltr">
                        <div>Is it possible that I have anomalous and
                          LLG peak, but I have no difference density
                          peak? In this case, is that because the model
                          I have is not good enough or the diffraction
                          data at this site of the model is missing?</div>
                      </div>
                    </blockquote>
                    <div><br>
                    </div>
                  </span>
                  <div>You should at a minimum see &gt; 1sigma density
                    in the 2mFo-DFc map, and if the site is unmodeled
                    (or modeled as a water) you should see an mFo-DFc
                    peak as well.  If neither of these applies, the
                    anomalous and LLG peaks are probably just noise.</div>
                  <div><br>
                  </div>
                  <div>-Nat </div>
                </div>
              </div>
            </div>
          </blockquote>
        </div>
        <br>
        <br clear="all">
        <div><br>
        </div>
        -- <br>
        <p>***************************************************</p>
        <p>Charles Chen</p>
        <p>Research Associate</p>
        <p>University of Pittsburgh School of Medicine</p>
        <p>Department of Anesthesiology</p>
        <p>******************************************************</p>
      </div>
    </blockquote>
    <br>
  </body>
</html>