Special Issue Preface pubs.acs.org/JPCA
Autobiography of Jacopo Tomasi
I
number of available positions was small and the examinations, lasting several days, were hard. For the academic year 1952−53 there were seven positions open for the whole class of sciences, from mathematics to physics, geology, life sciences, and chemistry. The contest was open to all Italian students, without limitations. In my year the number of candidates was about 400. Maintaining the position at the SNS was almost harder than being admitted the first year. There were a large number of internal courses, all of them compulsory and by far more complex and hard than the courses of Università di Pisa we had to follow at the same time. Not a single examination (at the University of Pisa and at SNS) could be completed with an evaluation lower than 24/30, and the total average had to be higher than 27/30. The internal courses for Chemistry at the SNS included a lot of mathematics and physics and some biology, physiology, geology, and chemistry. The main activities, laboratories included, took place at the University of Pisa. In those days the quality of teaching at the Institute of Chemistry of the University of Pisa was poor: too traditional and with a crazily limited access to laboratories. Anyway in my first university years I gained enough experience and manual skills to be a sufficiently good chemist of the old generation. In those days, however, the best was out of the Institute of Chemistry. A strong wind of renovation was moving the whole university (chemistry was lamentably lagging behind) and exciting the students of the SNS, the cream of the student body. But I shall not recall here all the philosophical, political, literary, and artistic issues that were raised and debated among us and had a big influence on my education. I shall limit myself to recall a few facts, which directly influenced my scientific career. During my first university year I was selected by Professor Derenzini to act as his aid in organizing a historical exhibition on the activities of physicists in Pisa during the preceding decades. The exhibition was connected to an important international Congress on Einstein, relativity, and the new physics. Derenzini, an excellent old professor who had a not negligible role in the development of quantum physics, chose me as an aid because I had impressed and amused him with my oral examination in physics during the SNS competition. After having ascertained that I was completely in the dark on this subject, he had asked me to plan an instrument for measuring the electric current by using a law connecting electricity and magnetism, which we had already discussed in the course of the examination. The whole discussion on the planning lasted long, but at last Derenzini was satisfied and concluded, “You have defined an improved version of the instrument devised in 1842. Congratulations!” The task Derenzini suggested me some months later was not verbal, it was practical. In our museum there was the first dynamo built by Pacinotti, which was at the origin of a debate
was born in 1934 in a small town on the coast of the Mediterranean Sea, near the border of Italy with France, the first son of a professor of humanities teaching in the high school of the nearby town of Imperia. My mother, a former teacher in elementary schools, was born within a large family with many relatives, while my father had no relatives. In my family life, peaceful and a bit secluded, games and studying were harmoniously intertwined. Until 1943 mine was a pleasant life: in one of the nicest places of the Italian Riviera, a tidy small town, with many trees, a splendid beach, a comfortable house with a large library I was freely using encouraged and helped by my parents. At the end of summer 1943 the evolution of political events in which Italy was engaged abruptly changed my family’s life. The truce between the Italian army and the Anglo-American allied forces caught us while still on holiday in a mountain resort. Luckily we succeeded in not being trapped in the mountains and returned safely to our home. Here, no more quiet and relaxed life. Bombings by Allied planes rapidly increased; the German forces took control of the territory with decision and brutality. The German army was rapidly building a strong fortified wall against a possible naval invasion by the Allied and there was an urgent need of manpower. After the war we learnt that about 35,000 men were taken on the streets of our region and kept working in duress at this wall. Actions of sabotage were beginning: the reaction of the SS was fast and severe. We searched for a haven far from the seafront and moved to a small property of ours on the nearby hills. After one month this site was repeatedly bombed and we moved to another place, where after a few months bombings and partisan activities expelled us again. A third place, secluded in the mountains, was found to be even worse, but there were no more possibilities to move. During those months we experienced famine, executions (shootings, hangings, blasting of hand grenades), rapes, scattered killings, demolitions of villages, and other similar things. This was a very singular way of achieving the education of a small boy whose most important previous activities had been reading books of good level and similar amenities. After April 1945 the horrors of what had been also a civil war were rapidly fading away, but the subsistence problems of my family took another form. During the last preceding years my father had to sustain large expenses (just to survive), completely depleting the fair amount of money inherited from his parents. At the same time inflation was soaring, while the wages of professors remained unchanged at the prewar levels. Life was hard day by day, and it was hardly possible to think of university studies for me. I had to gain myself financial support to attend university, and I had to abandon the idea of humanities and select curricula in the scientific branch, promising better professional conditions. One possibility was to gain a bursary at the “Scuola Normale Superiore di Pisa” (SNS), thought to be the best institution of high studies in Italy. I succeeded in a difficult task, as the © 2015 American Chemical Society
Special Issue: Jacopo Tomasi Festschrift Published: May 28, 2015 5041
DOI: 10.1021/acs.jpca.5b02577 J. Phys. Chem. A 2015, 119, 5041−5045
The Journal of Physical Chemistry A
Special Issue Preface
training by means of seminars. Private study task was to be performed during the night. Each team was instructed how to work and could constantly rely upon Scrocco’s personal support. He at once gained our esteem because of his exceptional manual ability and unusual capability of teaching while working. I was addressed to vibrational spectroscopy. The goal was to study specific aspects of overtones and other vibrational bands, with a strong emphasis on the development of theory. My first task (assigned because of the Derenzini experience) was the setup of the optical part of a big IR apparatus. This spectrometer was not old (it was a USA postwar gift) but was badly managed. The optical part was in rocky salt, very delicate to handle, and I spent many hours with Scrocco asking myself how to proceed. We found at last a good solution, but at the same time a more modern instrument arrived, affording a detection range more favorable for overtones. Measurements became a by far simpler routine. Scrocco decided then that my manual abilities were to be exploited in a different way: creating an analog computer for the evaluation of IR intensities. Since a good number of years the theory of intensities was sufficiently well described, but something was still missing. Scrocco encouraged me to study the old theoretical literature (an impressive amount of mathematical papers, mostly in German) to search for a theoretical clue leading to the use of an appropriate analog computer. I read many papers (I was the only one in our group able to read German) and my conclusion was that the only reasonable thing to do was extend to the third order of perturbation some treatments of spectroscopic properties defined by the second order only. Scrocco was satisfied, and I started building an analog computer based on the coupling of electric oscillators. To speed up thingsI had already spent on these spectroscopic follies an extra year after the end of the standard university course, and I was urging to discuss a thesisthe computer was limited to treat secondorder perturbations only for demonstration purposes. It was a very delicate task; each oscillator was to be of very small dimensions, with a very high response quality, placed within very effective shields to avoid improper resonances, and then treated with extreme care. The results were anyway very satisfactory, and Scrocco decided to collect financial support for building a very big analog computer. In the meantime I was not left continuing standard measurements of overtone intensities. Scrocco put me sitting at a desk in his office, with some blank sheets of paper in front and rapidly explained to me his desire of testing the performances of an unconventional approach to quantum mechanical calculations on molecules. The unconventional approach was the use of expansions of molecular orbitals no more on the atom centered functions with spherical symmetry but with atom functions having symmetry elements reflecting the molecular symmetry. I commented on this short explanation with the remark that perhaps the best approach was to modify Slater’s functions in the argument of the exponential. This was also Scrocco’s opinion. He gave me a pencil, asking me to initiate the work on the blank sheets in front of me, for the case of a simple molecule, H2. I have never forgotten the emotion, and anxiety, of initiating a task completely new to me, with oral comments intertwined while thinking and without any idea of how to proceed after the first step. Anyway, I did it with success, and after 2 or 3 hours spent that way at that desk we continued for years working shoulder by shoulder, first discussingwe had often very hard
on the priority in the creation of this instrument. The dynamo, as it was preserved in the museum, was not working, but Derenzini was not convinced and he wanted me to make an accurate restoration, without alterations, to show the scientists attending the Congress that Pacinotti’s dynamo was actually working. I succeeded in accomplishing this task and I made the demonstration in front of a very impressive panel of eminent scientists. Almost all the scientists involved in the elaboration of the last version of quantum theory were there: Schrödinger, Bohr, Born, Pauli, Heisenberg, and several others. (Dirac and Fermi were missing, as was Einstein, to whom the congress was devoted.) Thanks to the aid given to Derenzini also in other aspects of the exhibition, I had the opportunity of following the restricted discussions among these eminent scientists. My ideal goal became doing research in this field, with application to chemistry. I exposed my naif̈ purpose to Bonatti, professor of mineralogy and one of the few professors who were kind enough to hear the fantasies of students. He invited me to attend his laboratory and learn the techniques of X-ray diffraction of crystals. The laboratory had modern instrumentation, but the practice of X-ray diffraction was still at a stage requiring remarkable efforts for collecting and interpreting the data. “You need,” Bonatti explained to me, “very accurate manual skills, and you have just shown you have them; you need a particular interest in the computational aspects of physics, and you are just saying that this is your case.” So, in the following years I spent a good portion of my free time in Bonatti’s pleasant laboratory, fighting against the mathematical problem of the deconvolution of scattered signals. My best friends in the scientific disciplines were physicists almost all working in a new laboratory on microwave spectroscopy, at that time a new field satisfying, as I soon realized, all my expectations for my professional education. But it was not admitted by the SNS to change from chemistry to physics, even if the two disciplines were in the same faculty. I was therefore searching for a devious solution to get a Laurea in chemistry with a thesis in physics when the good solution to my problem appeared. At that time renovation actually reached also the Institute of Chemistry of the University of Pisa. The new professor of chemical physics, Eolo Scrocco, was a young physicist coming from the famous physics school of Rome. For his thesis he had done measurements of cosmic rays from high altitude planes. (During the war this was not a very safe place for a laboratory: a second plane was shot down by an Anglo-American fighter.) However, what was most important for his future work in Pisa was the very accurate training, in extension and depth, he had received in Rome to become a physicist: a physicist able to do effective work on the instrumentation and equipped with a solid knowledge of both classical and quantum theory of physics. With Scrocco the Institute of Chemistry immediately became open to senior students seeking a subject for their thesis. And so, after having waited years on the outer steps, we succeeded in entering inside the institute building. We were amazed at the mess. Several rooms were still in the conditions left by the big flood that had hit Pisa in November 1944 or were filled with the debris of 50 years of activity. Scrocco rapidly organized research teams on five topics. The first step for everybody was to become familiar with the existing instrumentation and related measurements, try to restore instruments no more properly working, and have collective 5042
DOI: 10.1021/acs.jpca.5b02577 J. Phys. Chem. A 2015, 119, 5041−5045
The Journal of Physical Chemistry A
Special Issue Preface
some compounds interesting for some specific colleagues. Catalytic effects, aromaticity, apicofilicity, delocalization, and lone pair are some scattered examples of chemical concepts conceived by the ingenuity of chemists in making experiments on real material specimens. The computer capabilities recently developed allowed the submission of such chemical concepts to independent tests, using no other chemical materials but a physical theory. Some concepts did not pass this test, the majority did, and an independent confirmation is the best way of strengthening a concept. I do not quote here specific examples of this activity: A few indications are given in the CV; in the bibliography reference is made to a big portion of the published material. (Other papers have been published without my name.) I prefer to make space for a few other topics. The first topic involves an aspect I just mentioned a few lines above. I have always thought it necessary to state explicitly and analyze in advance the motivations leading me to propose a new investigation and what type and quality of goals I was trying to reach. This approach is also useful to detect “surprises”: unexpected aspects sometimes opening vast new perspectives. The constant use of this approach also led me to produce some papers related to the methodology of research and connected problems. They have a vague scent of philosophy, and curious readers can easily find them in my bibliography. Another and perhaps more important topic I would like to take into consideration here is related to the best known part of my scientific activity, which will be discussed later on. Just starting from the basic papers of the novel theories on molecular vibrations, and by extension from the all new physics of matter, I got the uneasy feeling that all this was a good physics for an isolated piece of matter, but it neglected, or treated in too cursive a way, the fact that pieces of matter under investigation are in general under the influence of other bodies, or other physical factors. This uneasy feeling was mostly stirring me in reading German papers, but in English and French studies, too, I could perceive it. As said above, concluding this set of readings I suggested to Scrocco that we should focus our attention on the third-order corrections. However, my real opinion was that the part more cursively and approximately described was the one related to the effects of the surrounding medium on the vibrations. That was not the right moment to face the challenge of this theme, and I kept silence on my impressions. Revisiting these considerations in the following years I enlarged my perplexities on more basic aspects of the theory or better on the use we are making of them in the study of chemical phenomena. Basic aspects of the standard Copenhagen formulation of the quantum theory, as the complementary principle or the uncertainty principle, were not used to describe phenomena occurring in molecules, as the through-space and through-bonds interactions, the catalytic effect of pincemail motions in many enzymatic reactions, the opening and closure of ionic channels, and the effect of nearby substituents on electron ionization under the action of electromagnetic radiations (just to give some scattered examples). It was better to use a more modest formulation of the theory more based on a semiclassical description of material systems, from atoms to large collections of matter. Such semiclassical description was to be based on the standard quantum theory which had to give the ab initio descriptions of atoms and molecules and to pass then
discussionsand then writing: me writing, Scrocco looking at and commenting. After these intense meetings the work was also separately continued. I’ll quote an example. Our work was based for a long time on the elaborations of complex mathematical expressions. I kept as a souvenir some of my handwritten pages, with error corrections (very few, indeed!) and remarks added by Scrocco at home during the night. On my side, I remember the hours spent reporting with a pencil over big sheets, fixed on apposite desks, the values of the computed integrals one by one (and they arrived to be thousands), to be later recovered and transformed into a more condensed form. This was the epoch of mechanical computers. The Brunswiga machines, with their collections of gears and winches, were highly appreciated by our whole community at the Institute of Physical Chemistry, not only by the theoreticians involved in calculations but also by spectroscopists, electrochemists, and thermodynamicists, all involved in calculations, as ours was an Institute of Physical Chemistry, and therefore authorized, or better obliged, to crunch numbers. However, things were changing. I was obliged to leave my work to fulfill my duties with the army, and in the 18 months I spent there before coming back at work in Pisa the issue of electronic computers exploded in Italy as well as in other countries. In Italy the leading role was taken by our University, provided with an excellent team of physicists (coming from the already mentioned Roman school, as Scrocco) and of engineers (coming partly from the Olivetti laboratories) and by a new kind of scientists arriving from all over the world at the newly instituted Department of Informatics. The challenge of creating a large digital electronic computer of new conception started and was continued with celerity, among continuous new problems but also rapidly found solutions. Within a relatively short time there was in Italy the first efficient computer and the first large university department addressing all the issues for which a computer of this type was necessary. It was the first in continental Europe: a model for other countries. Our personal participation was enthusiastic and immediate, starting from the use of the first prototype of 1024 electronic units, which I used, with homemade programs, to compute the electronic structure of H2O, a triatomic molecule, and H2CO, a four atoms molecule. The number of atoms, and their reciprocal spatial positions within the molecule, were a big problem at that time. The approach I followed was later called “ab initio”, and we consistently followed this approach in the following years, not indulging to the temptation of using semiempirical, or semiclassical approaches, faster to use and allowing the examination of larger molecules. Our decision was the winning choice thanks to the rapid growth of computer dimensions and velocity, of course, but especially thanks to the possibility given by ab initio approaches of developing, refining, and testing interpretation tools. In the following years our work, accomplished with a few able and dedicated coworkers, covered the examination of a remarkable number of different phenomena: characteristics of chemical behavior of molecules and of their fragments, response to selected external factors, and similar items. I prefer to use such terms (rather abstract, I agree) instead of listing the classes of chemicals subjected to inquiry because our explicitly stated objective was to give a clear and operationally checked definition of the “chemical concepts” introduced and used in the chemical literature of the preceding 80 years and not to give a specific information about the structure and properties of 5043
DOI: 10.1021/acs.jpca.5b02577 J. Phys. Chem. A 2015, 119, 5041−5045
The Journal of Physical Chemistry A
Special Issue Preface
the original groups: The format used for this text was not suited for a continuation of the history of PCM. I am adding to these considerations a last remark. An interruption of the PCM history at the year 2000 does not tribute the right merit to the abundant, accurate, innovative, and still increasing contributions to the study in different media of the opto-electric and magnetic properties of molecules, starting from vibrations, and reaching an ever increasing degree of complexity. I consider these considerable progresses the fulfillment of a promise I made to myself about 60 years ago while reading the German papers on the theory of optical intensities, “I will consider in the future this subject which deserves a more accurate treatment.” I have written a sketch of a scientific autobiography lamentably incomplete on the scientific subjects and saying nothing about my private life. The private life is perhaps a topic of relevance also in scientific biographies. I add here some rapid statements. The years of SNS had a big impact on my private life. The most cherished friends, my wife, the husbands of my two twin sisters, they all came from the SNS. My wife, Carla Forti, is an extraordinary woman, of a very fiery temper, passionate, and of strong opinions. (We quarreled in the first years almost one time a day.) She is also very generous and easy to go in support of people needing it or of ideals worth of it. She has been a respected teacher of humanities, famous among generations of students, and wrote school books of remarkable commercial success. She was very active in the teacher’s union and also in Pisa’s local government institutions. In more recent years she came back to the historical studies of her university time on the political, theological, and social problems of the Hispanic colonization of America in the XVI century. She passed then to a very different type of history, mostly based on oral testimony, writing a book of great success, a sort of thriller: the killing of an eminent exponent of Pisa’s Jewish community. This book was also considered to be the reference book for a renewed methodology for oral history (but in my opinion even more important is the high literary value of this text). Carla has also been an excellent mother to our two children: Silvia and Simone. My daughter, Silvia, former student of the SNS, now teacher of history of art in Pisa, and her husband Marco Velli (another SNS former student, now professor of physics at the University of California in Los Angeles and currently heading a big project at NASA) have two sons, Filippo (21 years) and Paolo (15 years) that have yet to show what fruits their blossoming will produce. I like very much Silvia’s papers and books because of her vivid style and of the intellectual tension she deploys in analyzing unconventional aspects of the artistic productions of the past centuries. My son Simone followed my steps choosing the faculty of chemistry. After a start as an experimental organic chemist studying polymers, during his Ph.D. he moved into the synthesis of small molecules and gradually toward computations. Eventually, after a purely computational postdoctoral stint in Canada, he ended up working as a computational chemist in API process development for a pharmaceutical company in the U.K. He is married to Gail Rickard, also a chemist (they met in Calgary where both were postdoc students in physical chemistry) and they have a nice little girl (not yet 3 years of age) called Eleanor.
to classical descriptions when interactions among quantum systems were considered. I discussed for a long time this opinion with Scrocco, who was not fully convinced of explicitly abandoning the canonical formulation of quantum mechanics but was quite interested in looking at the results of tentative trials. The results of the use of semiclassical electric potential of molecules were impressive: there were at our disposal the wave functions of a set of molecules with a three-atoms cycle, cyclopropane, oxirane, aziridine, etc., for which we were performing studies on the structural properties. We computed electric potential maps, and the result was astonishing. The origin of all the effects we were discovering with the aid of numerical calculations was immediately visible by the simple inspection of the electric potential maps. There is no need to report details of the rapid development of this fortunate guess. We wrote with Scrocco a set of dossiers describing different possible applications of these computational tools. This set of dossiers was collected, printed, and distributed but was not considered a regular printed paper. For this reason it is not in the list of my publications. All the topics considered in those dossiers were satisfactorily treated, by us or by others. Several reviews have been written by me, others I wrote in collaboration with Scrocco; almost all were published in scattered collective books, consequently with a limited impact. In spite of this poor advertising action the use of the molecular potential gained an immense popularity, thanks, I think, to the inclusion of the subroutines for its calculation and graphical description in all the computer packages. Molecular biology and pharmacology in particular have been greatly sensitive to the new perspectives and possibilities given by this approach. Among the many possible outcomes of this approach there was the issue of solvent effects on molecular properties. We started working on this subject a bit later because I realized that it was actually a complex problem. In fact a whole theory of the solvation was necessary, more than the simple determination of the effect of solvent on the properties of a molecule. Other concepts were necessary, such as those of statistical mechanics. And other computational tools, such as those related to computational description by simulation of the behavior and properties of large assemblies of molecules, such as Monte Carlo and molecular dynamics procedures, have been also necessary. This work was done when Scrocco was no longer in Pisa, but his seminal influence is also evident in the first paper I published in 1981, three years after his retirement. I think that adding autobiographical comments on the last season of my scientific career is boring for me and of little use for possible readers. Summaries, necessarily short and with no details, say little to readers not familiar with the subject and are disappointing for people who have spent months or years in developing portions of this now considerable amount of methods collected under the acronym PCM (Polarizable Continuum Model). I prefer to direct the reader to a text I wrote about 15 years ago, which can be found at www.dcci.unipi.it/images/varie/ PCM_A_short_history.pdf. This document is written in an unusual form, and I hope it is suited for beginners searching for an orientation on the complex panorama of PCM. This text is concerning the work on PCM done until 2000. I stopped at that date because later there has been a remarkable increase in the number of contributions given by people not belonging to 5044
DOI: 10.1021/acs.jpca.5b02577 J. Phys. Chem. A 2015, 119, 5041−5045
The Journal of Physical Chemistry A
Special Issue Preface
To conclude, I must write about myself. Many elements should be evident for the readers of the preceding pages. I am a great reader of “ecumenical” tastes, interested in almost every discipline, even though the most frequented subjects are history and good literature. My library is large there are books everywhere at homebut not as ordered and specialized as that of my father’s. I love all kinds of art and I have a not so small collection of prints, from Dürer to the past century. I love the sea; my wife and I were everywhere the most enduring couple in swimming, going on for hours without rest along coasts of great beauty. We also love hiking, which unfortunately I was obliged to abandon, while my wife continues to spend many weekends climbing some mountain. For many years, from the university time until the retirement I was involved in some organization, political, professional, or else. I was an active member of student organizations, a member of the directory of the union of the university assistants, local section, and then, later, of the national bureau. A member of several scientific associations, for years I served as President, Vice President, or Secretary of the association of Physical Chemistry, the most quarrelsome association in the field of chemistry and physics, and tried to keep calm and tranquility among the members and in the relationships with other institutions. I had also a very active part in facing the problems of the university at the local and national levels. But I think that what I have written is enough to reassure the reader about my constant inclination to take action, I hope with beneficial results.
Jacopo Tomasi
Department of Chemistry and Industrial Chemistry, University of Pisa
5045
DOI: 10.1021/acs.jpca.5b02577 J. Phys. Chem. A 2015, 119, 5041−5045
