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John Pople (1925-2004) Cha đẻ lý thuyết điện
toán trong hóa học lượng tử
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Sinh năm 1925 tại Burnham-on-Sea, Somerset (Anh),
Pople nhận bằng tiến sĩ toán học năm 1951 tại Đại học Cambrigde. Một
năm sau đó, ông lập ra công thức cho một sơ đồ cơ bản để phát triển
những mô hình toán học phục vụ nghiên cứu phân tử mà không cần tiến
hành thí nghiệm. |
Sau một thời gian lãnh đạo Trung tâm nghiên cứu
vật lý cơ bản thuộc Phòng thí nghiệm vật lý quốc gia Anh gần London,
ông nhanh chóng cảm thấy không thích hợp với việc phải dành quá
nhiều thời gian cho công tác quản lý nên đã di cư sang Mỹ năm 1958.
Năm 1964, Pople trở thành giáo sư
vật lý hóa học tại trường Carnegie Tech, sau này trở thành đại học
Carnegie-Mellon, Pittsburgh (Mỹ). Ông được Nữ hoàng Anh Elizabeth II
phong tước Hiệp sĩ năm 2002 vì những đóng góp trong nghiên
cứu hóa học. Năm 1986, ông chuyển sang làm việc tại khoa hóa của Đại
học Northwestern (Mỹ).
John Pople, người giành giải Nobel năm 1998 vì
đóng góp to lớn trong quá trình phát triển các phương pháp điện toán
cho ngành hóa học. Ông qua đời ngày 15 tháng 3 năm 2004 tại
nhà riêng ở tuổi 78 vì bệnh ung thư gan.
Pople là người đã phát triển các kỹ thuật máy
tính phục vụ cho việc kiểm tra và xác định cấu trúc hóa học và những
chi tiết của vật chất. Chương trình máy tính do ông xây dựng đã được
hàng nghìn trường đại học và doanh nghiệp trên thế giới sử dụng. Đến
những năm 90 của thế kỷ trước, ông biên tập lại chương trình này,
kết hợp thêm với lý thuyết về mật độ của Walter Kohn, người đồng
nhận giải Nobel hóa học với ông. Kohn là nhà khoa học người Áo, làm
việc tại Đại học Santa Barbara (Mỹ). Nghiên cứu của ông này, bắt đầu
từ những năm 60, làm đơn giản hóa mô tả toán học về sự liên kết giữa
các nguyên tử tạo nên phân tử.
Cách tiếp cận bằng điện toán của Pople trong lĩnh
vực hóa học đã cho phép các nhà khoa học tạo ra những mô hình trên
máy tính của nhiều phản ứng hóa học, vốn là điều không thể hoặc rất
khó tái tạo trong phòng thí nghiệm. Công trình của ông có tầm ứng
dụng rất rộng, từ phục vụ nghiên cứu các vì sao dựa trên những dấu
hiệu hóa học đo qua kính viễn vọng, cho đến tìm hiểu phương thức mà
những chất gây ô nhiễm như freon phản ứng với tầng ozone. Trong lĩnh
vực y học, các nhà nghiên cứu cũng sử dụng phương pháp hóa học lượng
tử được vi tính hóa của Pople để tái tạo tác dụng của một số loại
thuốc chống lây nhiễm căn bệnh HIV
(theo Washington Post)
Autobiography - nobel.se
My early life was spent in
Burnham-on-Sea, Somerset, a small seaside resort town (population
around 5000) on the west coast of England. I was born on October 31,
1925 and lived there with my parents until shortly after the end of
the Second World War in 1946. No member of my family was involved in
any scientific or technical activity. Indeed, I was the first to
attend a university.
My father, Keith Pople, owned the principal men's clothing store in
Burnham. In addition to selling clothes in the shop, he used to
drive around the surrounding countryside with a car full of clothes
for people in remote farms and villages. He was resourceful and made
a fair income, considering the economic difficulties during the
depression of the 1930s. My great-grandfather had come to Burnham
around 1850 and set up a number of local businesses. He had a large
family and these were split up among his children. As a result, I
had relatives in many of the other businesses in the town. My
grandfather inherited the clothing shop and this passed to my father
when he returned from the army at end of the First World War.
My mother, Mary Jones, came from a farming background. Her father
had moved from Shropshire as a young man and had farmed near Bath
for most of his life. I suspect that he would have preferred to be a
teacher, for he had a large collection of books and encyclopedias.
He wanted my mother to be a schoolteacher, but this did not happen.
Instead, she became a tutor to children in a rich family and, later,
a librarian in the army during the first war. Most of her relatives
were farmers in various parts of Somerset and Wiltshire so, as small
children, my younger brother and I spent much time staying on farms.
Both of my parents were ambitious for their children; from an early
age I was told that I was expected to do more than continue to run a
small business in this small town. Education was important and seen
as a way of moving forward. However, difficulties arose in the
choice of school. There was a good preparatory school in Burnham
but, as part of the complex English class system, it was not open to
children of retail tradesmen, even if they could afford the fees.
The available alternative was unsatisfactory and my parents must
have agonized over what to do. Eventually, they decided to send us
to Bristol Grammar School (BGS) in the nearest big city thirty miles
away. BGS was the prime day school for boys, catering mainly to
middle class families resident in the city, although it received a
government grant for accepting about thirty boys a year from the
state elementary schools. I went there in the spring of 1936 at the
age of ten. Some arrangement had to be made for boarding and I used
to return home by train each weekend. This I found unappealing and
eventually I persuaded my parents to allow me to commute daily - two
miles by bicycle, twenty-five miles by train and one mile on foot. I
continued to do this during the early part of the war, a challenging
experience during the many air attacks on Bristol. Often, we had to
wend our way past burning buildings and around unexploded bombs on
the way to school in the morning. Many classes had to be held in
damp concrete shelters under the playing fields. In spite of all
these difficulties, the school staff coped well and I received a
superb education.
At the age of twelve, I developed an intense interest in
mathematics. On exposure to algebra, I was fascinated by
simultaneous equations and rapidly read ahead of the class to the
end of the book. I found a discarded textbook on calculus in a
wastebasket and read it from cover to cover. Within a year, I was
familiar with most of the normal school mathematical curriculum. I
even started some research projects, formulating the theory of
permutations in response to a challenge about the number of possible
batting orders of the eleven players in a cricket team. For a very
short time, I thought this to be original work but was mortified to
find n! described in a textbook. I then attempted to extend
n! to fractional numbers by various interpolation schemes.
Despite a lot of effort, this project was ultimately unsuccessful; I
was angry with myself when I learned of Euler's solution some years
later. However, these early experiences were valuable in formulating
an attitude of persistence in research.
All this mathematical activity was kept secret. My parents did not
comprehend what I was doing and, in class, I often introduced
deliberate errors in my exercises to avoid giving an impression of
being too clever. My grades outside of mathematics and science were
undistinguished so I usually ended up several places down in the
monthly class order. This all changed suddenly three years later
when the new senior mathematics teacher, R.C. Lyness, decided to
challenge the class with an unusually difficult test. I succumbed to
temptation and turned in a perfect paper, with multiple solutions to
many of the problems. Shortly afterwards, my parents and I were
summoned to a special conference with the headmaster at which it was
decided that I should be prepared for a scholarship in mathematics
at Cambridge
University. During the remaining two years at BGS, I received
intense personal coaching from Lyness and the senior physics master,
T.A. Morris. Both were outstanding teachers. The school, like many
others in Britain, attached great importance to the placement of
students at Oxford
or Cambridge. Most such awards were in the classics and I think that
the mathematics and science staff were very anxious to compete.
Ironically, during the last two years at BGS, I abandoned chemistry
to concentrate on mathematics and physics. In 1942, I travelled to
Cambridge to take the scholarship examination at
Trinity College,
received an award and entered the university in October 1943.
In the middle of the war, most young men of my age were inducted
into the armed forces at the age of seventeen. However, a small
group of students in mathematics, science and medicine was permitted
to attend university before taking part in wartime research projects
such as radar, nuclear explosives, code-breaking and the like. This
was a highly successful project and many of my predecessors in
earlier years made important contributions to the war effort. The
plan was to complete all degree courses in only two years, followed
by secondment to a government research establishment. In my case, I
completed Part II of the mathematical tripos in May 1945, just as
the European war was ending. In fact, it was hard to concentrate on
the examinations because of the noisy celebrations going on in the
streets outside. The government no longer had need for my services
and the university was under great pressure to make room for the
deluge of exservicemen as they were demobilized from the armed
forces. So, I had to leave Cambridge and take up industrial
employment for a period. This was with the Bristol Aeroplane
Company, close to where I had attended school. There was little to
do there and I had a period of enforced idleness as changing
employment was illegal at the time (part of the obsession for a
planned economy in postwar Britain).
In 1945, I had little idea of what my future career might be. My
interest in pure mathematics began to wane; after toying with
several ideas, I finally resolved to use my mathematical skills in
some branch of science. The choice of a particular field was
postponed, so I devoted much of my time to pestering government
offices for permission to return to Cambridge and resume my studies.
In the late summer of 1947, I finally received a letter informing me
that an unexpectedly large number of students had failed their
examinations and a few places were available. So, in October 1947, I
returned to Cambridge to begin a career in mathematical science.
Cambridge in 1947 had greatly changed since 1943. The university was
crowded with students in their late twenties who had spent many
years away at the war. In addition, the lectures were given by the
younger generation who had also been away on research projects.
There was a general air of excitement as these people turned their
attention to new scientific challenges. I remained as a mathematics
student but spent the academic year 1947-8 taking courses in as many
branches of theoretical science as I could manage. These included
quantum mechanics (taught in part by
Dirac), fluid dynamics, cosmology and statistical mechanics.
Most of the class opted for research in fundamental areas of physics
such as quantum electrodynamics which was an active field at the
time. I felt that challenging the likes of
Einstein and Dirac was overambitious and decided to seek a less
crowded (and possibly easier) branch of science. I developed an
interest in the theory of liquids, particularly as the statistical
mechanics of this phase had received relatively little attention,
compared with solids and gases. I approached Fred Hoyle, who was
giving the statistical mechanics lectures (following the death of
R.H. Fowler). However, his current interests were in the fields of
astrophysics and cosmology, which I found rather remote from
everyday experience. I next approached Sir John Lennard-Jones (LJ),
who had published important papers on a theory of liquids in 1937.
He held the chair of theoretical chemistry at Cambridge and was
lecturing on molecular orbital theory at the time. When I approached
him, he told me that his interests were currently in electronic
structure but he would very possibly return to liquid theory at some
time. On this basis, we agreed that I would become a research
student with him for the following year. Thus, after the
examinations in June 1948, I began my career in theoretical
chemistry at the beginning of July. I had almost no chemical
background, having last taken a chemistry course at BGS at the age
of fifteen. Other important events took place in my life at this
time. In late 1947, I was attempting to learn to play the piano and
rented an instrument for the attic in which I lived in the most
remote part of Trinity College. The neighbouring room was occupied
by the philosopher Ludwig Wittgenstein, who had retired to live in
primitive and undisturbed conditions in the same attic area. There
is some evidence that my musical efforts distracted him so much that
he left Cambridge shortly thereafter. In the following year, I
sought out a professional teacher. The young lady I contacted, Joy
Bowers, subsequently became my wife. We were married in Great St.
Mary's Church, Cambridge in 1952, after a long courtship. Like many
other Laureates, I have benefit immeasurably from the love and
support of my wife and children. Life with a scientist who is often
changing jobs and is frequently away at meetings and on lecture
tours is not easy. Without a secure home base, I could not have made
much progress. The next ten years (1948-1958) were spent in
Cambridge. I was a research student until 1951, then a research
fellow at Trinity College and finally a lecturer on the Mathematics
Faculty from 1954 to 1958. Cambridge was an extraordinarily active
place during that decade. I was a close observer of the remarkable
developments in molecular biology, leading up to the double helix
papers of
Watson and
Crick. At the same time, the X-ray group of
Perutz and
Kendrew (introduced to the Cavendish Laboratory by
Lawrence Bragg) were achieving the first definitive structures
of proteins. Elsewhere, Hoyle, Bondi and Gold were arguing their
case for a cosmology of continuous creation, ultimately disproved
but vigorously presented. Looking through the list of earlier Nobel
laureates, I note a large number with whom I became acquainted and
with whom I interacted during those years as they passed through
Cambridge.
In the theoretical chemistry department, LJ was professor and Frank
Boys started as lecturer in September 1948. I began research with
some studies of the water molecule, examining the nature of the lone
pairs of electrons. This was an initial step towards a theory of
hydrogen bonding between water molecules and a preliminary, rather
empirical study of the structure of liquid water. This fulfilled my
initial objective of dealing with properties of liquids and gained
me a Ph.D. and a research fellowship at Trinity College. This highly
competitive stage accomplished, I was able to relax a bit and
formulate a more general philosophy for future research in
chemistry. The general plan of developing mathematical models for
simulating a whole chemistry was formulated, at least in principle,
some time late in 1952. It is the progress towards those early
objectives that is the subject of my Nobel lecture.
At that early date, of course, computational resources were limited
to hand calculators and very limited access to motorized electric
machines. So my early notes show attempts to simplify theories
enough to turn them into practical possibilities. The work
paralleling studies of Pariser and Parr led to what became known as
PPP theory. This was not a complete model but rather one applicable
to systems with only one significant electron per atom. It did fit
the general form of conjugated hydrocarbons and achieved some
notoriety. In 1953, Bob Parr came to Cambridge to spend a year with
Frank Boys. We shared an office and had many valuable discussions;
he was to have a major influence on my future. I talked about PPP
theory when I began to speak at international meetings in 1955.
In addition to the PPP work, I started theoretical work on other
topics in physical chemistry. I began supervision of research
students in 1952, beginning with David Buckingham, who completed a
masterly thesis on properties of compressed gases. He was the first
of a long list of remarkably able and dedicated students who have
worked with me over the years. In 1954, LJ was succeeded as
professor of theoretical chemistry by Christopher Longuet-Higgins,
who was joined by Leslie Orgel shortly afterwards. I continued to
spend a lot of time in the chemistry department, although by then I
had undertaken new teaching responsibilities as a lecturer in
mathematics. The department was crowded and active in those years.
Among the many visitors were
Linus Pauling,
Robert Mulliken, Jack Kirkwood, Clemens Roothaan and Bill
Schneider. Frank Boys was also managing a lively group of students.
At the end of 1955, I developed an interest in nuclear magnetic
resonance, which was then emerging as a powerful technique for
studying molecular structure. At the urging of Bill Schneider, I
agreed to spend two summers (1956 and 1957) at the National Research
Council in Ottawa, Canada, working on the theoretical background of
NMR. This was extremely stimulating for, at that time, we were
measuring the spectra and interpreting the nuclear spin behaviour of
many standard chemicals for the first time. My time there with Bill
and Harold Bernstein led to a book, High Resolution Nuclear
Magnetic Resonance, which was well received. This area was the
main emphasis of my research during the final years in Cambridge.
By 1958, I had become dissatisfied with my mathematics teaching
position at Cambridge. I had clearly changed from being a
mathematician to a practicing scientist. Indeed, I was increasingly
embarassed that I could no longer follow some of the more modern
branches of pure mathematics, in which my undergraduate students
were being examined. I therefore resolved to seek a new job with
greater scientific content. After some hesitation, I accepted a
position as head of the new Basics Physics Division at the National
Physical Laboratory near London. This involved direction of
experimental work and a considerable amount of administration. When
I took the job, I hoped that the administrative burden would not be
large enough to interfere with my research programme. Although I was
given plenty of help, this turned out not to be so and I had a
rather fallow period while I was there.
In the spring of 1961, I organized an international conference in
Oxford, along with Charles Coulson and Christopher Longuet-Higgins.
Bob Parr was an invited speaker and, during a break, he urged me to
come and spend a sabbatical year at Carnegie Institute of Technology
in Pittsburgh. This was an attractive suggestion and I arranged to
come for the academic year 1961-2 with my family. By this time, Joy
and I had three children and were expecting a fourth. We arrived in
September, accompanied by a charming young Swedish au pair,
Elisabeth Fahlvik. One of the most delightful side-effects of
winning the Nobel Prize is the opportunity to meet her again after a
gap of over thirty-six years.
By the time we arrived in Pittsburgh, Bob Parr had decided to leave
for Johns Hopkins
University and he did, in fact, leave in January. Nevertheless,
we had a delightful year, travelling as a family over much of the
eastern part of the U.S.A. During this period, I made up my mind to
abandon my administrative job and seek an opportunity to devote as
much time as possible to chemical research. I was approaching the
age of forty, with a substantial publication record, but had not yet
held any position in a chemistry department. When we returned to
England in June, 1962, it was not clear where we might go for there
were opportunities both in the U.K. and the U.S.A. Eventually, after
much debate, we decided to return to Pittsburgh in 1964. Leaving
England was a painful decision and we still have some regrets about
it. However, at that time, the research environment for theoretical
chemistry was clearly better in the U.S.
On my return to Pittsburgh, I resolved to go back to the fundamental
problems of electronic structure that I had contemplated abstractly
many years earlier. Prospects of really implementing model
chemistries had improved because of the emerging development of
high-speed computers. I was late in recognizing the role that
computers, would play in the field – I should not have been, for
Frank Boys was continually urging the use of early machines back in
Cambridge days. However, by 1964, it was clear that the development
of an efficient computer code was one of the major tasks facing a
practical theoretician and I learned the trade with enthusiasm.
Mellon Institute, where I had an adjunct appointment, acquired a
Control Data machine in 1966 and my group was able to make rapid
progress in the dingy deep basement of that classic building. In
1967, Carnegie Tech and Mellon Institute merged to become
Carnegie-Mellon
University (CMU) and I remained on the faculty there until 1993.
Almost all of the work honored by the Nobel Foundation was done at
CMU. That institution deserves much of the credit for their
continuing support and encouragement over many years.
The scientific details of the Pittsburgh work are related, in part,
in the accompanying lecture. Over the years, we were able to keep
abreast with the rapid developments in computer technology. Around
1971, the work was moved to a Univac 1108 machine and then, in 1978,
we were fortunate enough to acquire the first VAX/780 minicomputer
from the Digital Equipment Corporation for use entirely within the
chemistry department. This became a valuable workhorse as we began
to distribute programs to the general chemical community. In more
recent years, of course, the techniques have become available on
small work stations and personal computers. The astonishing progress
made in computer technology has had profound consequences in so many
branches of theoretical science.
Our children were mostly brought up and educated in the Churchill
suburb east of Pittsburgh. Each summer, we took them back to England
for an extended period. By 1979, all had gone away and Joy and I
decided to move again to Illinois, where our daughter had settled.
In 1981, we set up house in Rogers Park, Chicago and then moved to
Wilmette in 1988. Our family is now scattered in Chicago, Houston,
Pittsburgh and Cork, Ireland. We have been blessed with ten
grandchildren (an eleventh expected), who greatly enrich our lives
in many ways.
From 1981 to 1993, I continued to run my research group in
Pittsburgh, commuting frequently and communicating with my students
by telephone and modem.
Northwestern
University kindly offered me an adjunct appointment and I became
a full member of their faculty in 1993. I am very grateful to them
for the opportunity to continue my research programme and interact
with other members of the chemistry department.
I have had many opportunities to visit universities all over the
world in the past fifty years. Among the most rewarding have been
frequent trips to Australia and New Zealand, where Joy and I have
wintered no fewer than nine times since 1982. The campus of the
Australian National
University, where Leo Radom became Professor after spending time
with me as a postdoctoral fellow from 1968 to 1972, has become a
second academic home – a great place for relaxed contemplation.
Israel and Germany are other countries with which I have become
closely associated, having visited and collaborated many times. In
the 1980s, I held a von Humboldt Award, which allowed me to spend
some time in Erlangen, where I collaborated with Paul Schleyer on a
large number of applications of the theory. In Israel, I have
visited and lectured at all universities, including a period as
Visiting Professor at the
Technion,
Haifa. In 1992, I was fortunate enough to receive the Wolf Prize in
Chemistry at a ceremony in the Knesset.
I must emphasize that my contribution to quantum chemistry has
depended hugely on work by others. The international community in
our field is a close one, meeting frequently and exchanging ideas
freely. I am delighted to have had students, friends and colleagues
in so many nations and to have learned so much of what I know from
them. This Nobel Award honours them all.
From
Les Prix Nobel 1998.
John Pople died the 15th of
March, 2004
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