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

João M. Damas jmdamas at itqb.unl.pt
Tue Mar 4 17:05:56 CET 2014


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


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