[gmx-users] g_sas: unable to reproduce data from original article of the DCLM (Eisenhaber1995)

João M. Damas jmdamas at itqb.unl.pt
Wed Mar 5 03:27:32 CET 2014


Thanks to Teemu, we found that the "-pbc yes" results is not a bug after
all (my bad). It is solved here: http://redmine.gromacs.org/issues/1449.
The final results are in Attached Table 4.

To conclude, going back to the "-nopbc" bug found, the following plot is a
"real case" example of the difference one can see between a fixed and a
non-fixed g_sas run. I plot the contact area [there are several ways to
calculate this, I show one of them] between a ligand and a protein along
simulation time. Negative contact areas and the spikes were the puzzling
results I mentioned in the beginning of this thread.

[image: Inline image 1]

I would like to thanks David and Teemu for their help on this matter.

Best,
João

--
Attached Table 4
met  - method used, anl=analytical method, num=numerical method (DCLM)
dots - number of points used for the numerical method
src  - source of the data, paper=Eisenhaber1995, ASC=ASC software,
       g463{sp,fx}=g_sas of GMX4.6.3 {single precision,fix
3199<https://gerrit.gromacs.org/#/c/3199/>
}

pbc  - PBC flag for g_sas, yes=-pbc, no=-nopbc
Areas are in square angstrom
======================================================
  met  dots     src  pbc      4PTI      3FXN      1TIM
======================================================
  anl         paper        3973.80   6943.80  20002.80
  anl           ASC        3973.81   6943.80  20002.80

  num   122   paper        3961.40   6968.30  19970.90
  num   122     ASC        3961.44   6968.33  19970.90
  num   122  g463sp  yes   3957.81   6955.99  20004.20
  num   122  g463sp   no   4169.21   7731.63  24080.20
  num   122  g463fx  yes   3957.81   6955.99  20004.20
  num   122  g463fx   no   3957.81   6955.99  20004.20

  num   362   paper        3971.80   6933.40  19997.10
  num   362     ASC        3971.79   6933.37  19997.10
  num   362  g463sp  yes   3969.92   6936.20  20016.70
  num   362  g463sp   no   4195.02   7704.70  24132.10
  num   362  g463fx  yes   3969.92   6936.20  20016.70
  num   362  g463fx   no   3969.92   6936.20  20016.70

  num   642   paper        3967.90   6944.40  19998.70
  num   642     ASC        3967.78   6944.37  19998.70
  num   642  g463sp  yes   3966.21   6941.26  20013.40
  num   642  g463sp   no   4188.63   7701.99  24119.00
  num   642  g463fx  yes   3966.21   6941.26  20013.40
  num   642  g463fx   no   3966.21   6941.26  20013.40

  num  1002   paper        3974.10   6939.10  20012.20
  num  1002     ASC        3974.07   6939.12  20012.20
  num  1002  g463sp  yes   3973.51   6939.81  20027.50
  num  1002  g463sp   no   4193.60   7700.78  24143.10
  num  1002  g463fx  yes   3973.51   6939.81  20027.50
  num  1002  g463fx   no   3973.51   6939.81  20027.50

  num  1472   paper        3975.70   6943.30  19997.00
  num  1472     ASC        3975.70   6943.35  19996.90
  num  1472  g463sp  yes   3975.88   6943.96  20012.40
  num  1472  g463sp   no   4198.08   7709.30  24123.30
  num  1472  g463fx  yes   3975.88   6943.96  20012.40
  num  1472  g463fx   no   3975.88   6943.96  20012.40
======================================================


On Tue, Mar 4, 2014 at 4:05 PM, João M. Damas <jmdamas at itqb.unl.pt> wrote:

> Done: http://redmine.gromacs.org/issues/1449
>
> João
>
>
> On Tue, Mar 4, 2014 at 6:56 AM, David van der Spoel <spoel at xray.bmc.uu.se>wrote:
>
>> On 2014-03-04 04:39, João M. Damas wrote:
>>
>>> Hello Teemu,
>>>
>>> Thank you! I am glad the GROMACS team is concerned about this particular
>>> problem.
>>> And I am sorry for my late reply.
>>>
>>> For the sake of conciseness, so we do not get lost in the data, I am only
>>> showing the single precision results (we may bring double precision later
>>> on again). Also, since GROMACS 4.0.4 is flawed in the -pbc flag, as Teemu
>>> said, I also excluded it from these results (it is not going to get
>>> corrected anyway).
>>>
>>> I compiled a GROMACS version 4.6.3 with the fix presented in
>>> https://gerrit.gromacs.org/#/c/3199/ (in single precision).
>>>
>>> I repeated the tests and the results are presented in Attached Table 3.
>>>
>>>     - the fix brings the -nopbc results close (within 1 square angstrom)
>>> to
>>>
>>>     the ones obtained by ASC, except for 1TIM where the difference is
>>> within
>>>     10-20 square angstrom. Maybe 1TIM has a difficult shape, because ASC
>>> also
>>>     had the largest difference between numerical DCLM and the analytical
>>> method
>>>     in this protein.
>>>     - the "-pbc yes" results though, do not change (which is normal,
>>>
>>>     considering the flag is working in this version and the fix is
>>> inside a
>>>     conditional expression that depends on the -pbc flag). It continues
>>> to
>>>     baffle me why this is happening. If the molecule is inside the box
>>> and far
>>>     from the edges (again, a test using a .gro created by editconf -d 5
>>> gave
>>>     the same exact table as Attached Table 3), I see no reason why these
>>>     results should be different...
>>>
>>> So, I think Bug #1445 <http://redmine.gromacs.org/issues/1445> is indeed
>>>
>>> solved, but we still need to solve an unknown bug with "-pbc yes".
>>> Should I
>>> open a new bug related to this in the redmine?
>>>
>>
>> In short, yes. If the protein is in the center of the box with no
>> periodic contacts the result should be the same as without pbc.
>>
>>
>>> I can perform more tests, if anyone has more ideas.
>>>
>>> Best,
>>> João
>>>
>>> --
>>> Attached Table 3
>>> met  - method used, anl=analytical method, num=numerical method (DCLM)
>>> dots - number of points used for the numerical method
>>> src  - source of the data, paper=Eisenhaber1995, ASC=ASC software,
>>>         g463{sp,fx}=g_sas of GMX4.6.3 {single precision,fix
>>> 3199<https://gerrit.gromacs.org/#/c/3199/>
>>>
>>> }
>>> pbc  - PBC flag for g_sas, yes=-pbc, no=-nopbc
>>> Areas are in square angstrom
>>> ======================================================
>>>    met  dots     src  pbc      4PTI      3FXN      1TIM
>>> ======================================================
>>>    anl         paper        3973.80   6943.80  20002.80
>>>    anl           ASC        3973.81   6943.80  20002.80
>>>
>>>    num   122   paper        3961.40   6968.30  19970.90
>>>    num   122     ASC        3961.44   6968.33  19970.90
>>>    num   122  g463sp  yes   3825.86   6257.83  19867.90
>>>    num   122  g463sp   no   4169.21   7731.63  24080.20
>>>    num   122  g463fx  yes   3825.86   6257.83  19867.90
>>>    num   122  g463fx   no   3957.81   6955.99  20004.20
>>>
>>>    num   362   paper        3971.80   6933.40  19997.10
>>>    num   362     ASC        3971.79   6933.37  19997.10
>>>    num   362  g463sp  yes   3838.35   6248.43  19886.80
>>>    num   362  g463sp   no   4195.02   7704.70  24132.10
>>>    num   362  g463fx  yes   3838.35   6248.43  19886.80
>>>    num   362  g463fx   no   3969.92   6936.20  20016.70
>>>
>>>    num   642   paper        3967.90   6944.40  19998.70
>>>    num   642     ASC        3967.78   6944.37  19998.70
>>>    num   642  g463sp  yes   3831.64   6255.64  19882.70
>>>    num   642  g463sp   no   4188.63   7701.99  24119.40
>>>    num   642  g463fx  yes   3831.64   6255.64  19882.70
>>>    num   642  g463fx   no   3966.21   6941.26  20013.60
>>>
>>>    num  1002   paper        3974.10   6939.10  20012.20
>>>    num  1002     ASC        3974.07   6939.12  20012.20
>>>    num  1002  g463sp  yes   3840.58   6250.14  19897.40
>>>    num  1002  g463sp   no   4193.60   7700.64  24143.10
>>>    num  1002  g463fx  yes   3840.58   6250.14  19897.40
>>>    num  1002  g463fx   no   3973.51   6939.68  20027.50
>>>
>>>    num  1472   paper        3975.70   6943.30  19997.00
>>>    num  1472     ASC        3975.70   6943.35  19996.90
>>>    num  1472  g463sp  yes   3841.69   6256.92  19882.80
>>>    num  1472  g463sp   no   4198.08   7709.30  24123.30
>>>    num  1472  g463fx  yes   3841.69   6256.92  19882.80
>>>    num  1472  g463fx   no   3975.88   6943.96  20012.40
>>> ======================================================
>>>
>>>
>>>
>>>
>>> On Fri, Feb 28, 2014 at 4:49 AM, Teemu Murtola <teemu.murtola at gmail.com>
>>> wrote:
>>>
>>>  Hi,
>>>>
>>>> On Thu, Feb 27, 2014 at 4:09 PM, Teemu Murtola <teemu.murtola at gmail.com
>>>>
>>>>> wrote:
>>>>>
>>>>
>>>>  I'll post additional information once I have had time to test more
>>>>> cases.
>>>>>
>>>>>
>>>> I have now created <http://redmine.gromacs.org/issues/1445> to track
>>>> the
>>>> issue, and uploaded a fix to Gerrit: <https://gerrit.gromacs.org/#/
>>>> c/3199/
>>>>
>>>>> .
>>>>>
>>>> My current set of tests is here: <https://gerrit.gromacs.org/#/c/3200/>
>>>>
>>>> Looking at the history, as described in the Redmine issue, this should
>>>> explain incorrect results with -nopbc. The Redmine issue also provides
>>>> an
>>>> explanation for why 4.0.4 gives the same results with -pbc and -nopbc.
>>>> This
>>>> doesn't explain why it gives a slight underestimation with -pbc in
>>>> 4.6.3,
>>>> but you could try repeating the tests with the fixed version to see
>>>> whether
>>>> the PBC treatment or something else is giving rise to the
>>>> underestimation.
>>>>
>>>> Best regards,
>>>> Teemu
>>>> --
>>>> Gromacs Users mailing list
>>>>
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>>>>
>>>
>>>
>>>
>>
>> --
>> David van der Spoel, Ph.D., Professor of Biology
>> Dept. of Cell & Molec. Biol., Uppsala University.
>> Box 596, 75124 Uppsala, Sweden. Phone:  +46184714205.
>> spoel at xray.bmc.uu.se    http://folding.bmc.uu.se
>> --
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>>
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>
>
>
> --
> João M. Damas
> PhD Student
> Protein Modelling Group
> ITQB-UNL, Oeiras, Portugal
> Tel:+351-214469613
>



-- 
João M. Damas
PhD Student
Protein Modelling Group
ITQB-UNL, Oeiras, Portugal
Tel:+351-214469613


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